Misure spettrometriche gamma di concentrazioni radionuclidiche in campioni ambientali e alimentari in situazioni di emergenza

Application of Electron Spin Resonance technique in neutron dosimetry

Along with the Neutron Capture Therapy (NCT) development and with the use of thermal neutrons for radiotherapeutic purposes, many efforts have been devoted to the beam characterization in order to optimize the therapy procedures. Reliable dosimetric measurements should be able to determine the various components (neutronic and photonic) of the mixed beam usually employed for therapy [1]. We have studied the effect of the additive such as gadolinium and 10B-boric acid on the neutron sensitivity of alanine ESR dosimeters exposed to a gamma and mixed (n, gamma) field mainly composed by thermal neutrons. We have chosen both this additive nuclei because of their very high capture cross section t…

Epoxy based matrices for structural composites prepared by ionizing radiation. Morphological and thermal behaviour

Simulazione di un irradiatore gamma con codice Monte Carlo: valutazione della dose e verifica dei contributi strutturali

Si è utilizzato il codice di calcolo Montecarlo MCNP4C per simulare sia le sorgenti che i materiali strutturali dell’irradiatore IGS3, al fine valutarne i loro contributi. Il numero di storie simulate è stato fissato in modo da ottenere un errore casuale abbastanza piccolo. Si sono utilizzati due scenari: uno in presenza del ripiano di appoggio dei campioni da irradiare ed uno senza. I punti dose sono stati posti a tre distanze dalle sorgenti e a tre quote rispetto al piano di appoggio. Negli stessi punti–dose sono state eseguite delle misure sperimentali utilizzando due coppie di sorgenti di radioattive. Sia le simulazioni che i punti sperimentali sono stati messi in relazione con i risult…

Gamma-ray irradiation tests on CCD and CMOS sensors used in imaging techniques

Technologically-enhanced electronic devices are used in various fields as space imaging or diagnostic techniques in medicine. The devices can be exposed to intense radiation fluxes over time which may impair the functioning of the same apparatus, in particular in space applications. In this paper we report the results of a gamma irradiation tests on imaging sensors simulating the space radiation over a long time period. Two types of sensors are taken into consideration: CCD (Charge-Coupled Device) sensors and CMOS based on technology MOS (Metal Oxide semiconductor) used for the realization of transistors widely used in consumer electronics. The devices are supplied by Techno System (Italy),…

Identificazione tramite termoluminescenza di gamberi e scampi irradiati: confronto tra le due metodiche di estrazione dei silicati raccomandate nel protocollo europeo

METODI FISICO E BIOLOGICO DI IDENTIFICAZIONE DI ALIMENTI IRRADIATI CONTENENTI CELLULOSA ATTRAVERSO L'USO DELLA DNA COMET ASSAY E DELLE SPETTROSCOPIA ESR

Electrically conductive polyaniline-hydrogel composites, produced via “in situ” dispersion polymerization

Low Dose-Rate, High Total Dose Set-Up for Rad-Hard CMOS I/O Circuits Testing

In this paper, the planning of low dose-rate, high total dose testing campaign for I/O circuits is reported. In particular, the paper describes all development steps, starting from the rad-hard I/O circuits design and the implementation of the test-chip, which is meant to allow comparative testing between rad-hard and standard devices. The designed experimental setup permits in situ measurements, therefore the circuits behavior can be remotely monitored for very long periods. This feature enables low dose-rate testing up to very high dose.

A practical and transferable methodology for dose estimation in irradiated spices, based on thermoluminescence dosimetry

Abstract The thermoluminescence technique is recommended by the European Committee for Standardization for the detection of irradiated food containing silicates as contaminants. In this work, the applicability of the thermoluminescence technique as a quantitative method to assess the original dose in irradiated oregano was studied; the additive-dose method was used, with reirradiation doses up to 600 Gy. The proposed new procedure allows to clearly discriminate irradiated from unirradiated samples, even after one year storage, and it gives an acceptable estimation of the original dose; the overall modified procedure requires only one day to be completed.

The additive dose method for dose estimation in irradiated oregano by thermoluminescence technique

The ionizing radiation treatment of food is nowadays a worldwide recognized tool for food preservation, provided that proper and validated identification methods are available and used. The thermoluminescence (TL) technique is one of the physical methods recommended by the European Committee for Standardization to distinguish irradiated from not irradiated samples, for food containing silicate minerals as contaminants, such as spices and aromatic herbs, which are among the most frequently irradiated foods. The experimental results presented in this work show that, at least up to the highest tested doses (2 kGy), it is possible to set up a procedure to estimate the actual dose in the irradia…

Electron paramagnetic resonance investigation on the hyperfine structure of the E’_delta center in amorphous silicon dioxide

Assessment of contamination of <em>Salmonella</em> spp. in imported black pepper and sesame seed and salmonella inactivation by gamma irradiation

This study shows the frequency of seeds samples contaminated by Salmonella spp. collected randomly from local markets; on 30 black pepper sample no contaminated sample was found while Salmonella spp. was detected in 3 of 36 (8.3%) analyzed sesame samples; three different serotypes were identified: S. Montevideo, S. Stanleyville e S. Tilene. The efficacy of gamma irradiation to inactivate Salmonella Montevideo in black pepper and sesame irradiated between 1 and 5 kGy was evaluated. 3 kGy is sufficient to reduce of 3-4 log CFU/g; whereas 5 kGy have been need to reduce 5.5-6 log CFU/g for samples of black pepper and sesame. No statistically significant differences were found between black pepp…

INDAGINE MICROBIOLOGICA SU MAIALE IRRADIATO A SCOPO CONSERVATIVO E STIMA DELLA DOSE TRAMITE GC/MS

Electron paramagnetic resonance line shape investigation of the 29Si hyperfine doublet of the E’_gamma center in a-SiO2

Electron Spin Resonance and Thermoluminescence dating of shells and sediments from Sambaqui (shell mound) Santa Marta II, Brazil

In Tupi, the word Sambaqui means “mound of shells”. These archaeological sites are cultural vestiges left by the prehistoric occupation of the Brazilian coast from five to six thousand years ago. Mollusks, fishes, and other marine edible foods were important for the survival of this population. The remains of foods, mainly shells, were heaped up, giving a mound of different proportions, which became part of the landscape of the Brazilian coastal plain. Due to the large number of Sambaquis in Brazil and considering that Sambaqui Santa Marta II, Laguna, SC, has not yet been dated, Electron Spin Resonance (ESR) measurements were performed in aragonite shells collected from different layers of …

Una rapida metodica di estrazione del 2-dodecilciclobutanone per la identificazione tramite GC/MS di alimenti irradiati contenenti grassi

Ottimizzazione della protezione di un irradiatore neutronico per test di componenti elettronici

Sono descritte la progettazione e realizzazione di uno schermo mobile per l’irradiatore neutronico Am-Be del Dipartimento DEIM utilizzato per testare la vita media di funzionamento di dispositivi elettronici sottoposti a campi di radiazioni. Il numero di componenti da provare può essere significativamente elevato in relazione all’attendibilità del test e alla statistica dei risultati che si vuole ottenere, con un conseguente incremento della dose all’operatore. Per ridurre il valore di dose-rate totale del campo misto (gamma-neutroni) di radiazione emergente dall’irradiatore si è realizzato uno schermo addizionale di piombo, ferro e acido borico con dimensioni ottimizzate dal punto di vista…

Procedura di calibrazione di sistemi dosimetrici a film radio-cromici GAFCHROMIC® mod. HD-V2

I sistemi dosimetrici a film radiocromici vengono utilizzati nelle misure della dose assorbita da vari materiali sottoposti a radiazioni ionizzanti, nei quali avvengono reazioni chimiche che intensificano le bande ottiche d’assorbanza determinata, quest’ultima, tramite l’utilizzo di uno spettrofotometro. L’impiego di questi sistemi comporta una preliminare calibrazione degli stessi in riferimento a standard internazionali. La dose rilevata fa riferimento generalmente alla dose assorbita in acqua anche se è possibile determinare la stessa in altri materiali tramite opportuni fattori correttivi. L’interesse verso questi sistemi dosimetrici è relativo all’impiego in processi industriali d’irra…

Gamma-ray irradiation tests of CMOS sensors used in imaging techniques

Technologically-enhanced electronic image sensors are used in various fields as diagnostic techniques in medicine or space applications. In the latter case the devices can be exposed to intense radiation fluxes over time which may impair the functioning of the same equipment. In this paper we report the results of gamma-ray irradiation tests on CMOS image sensors simulating the space radiation over a long time period. Gamma-ray irradiation tests were car ried out by means of IGS-3 gamma irradiation facility of Palermo Uni ver sity, based on 60Co sources with dif fer ent ac tiv i ties. To re duce the dose rate and re al ize a nar row gamma-ray beam, a lead-collimation sys tem was pur posely …

Uno studio per l’implementazione della strumentazione della stazione di prelievo di particolato atmosferico del DIN di Palermo

Electron Paramagnetic Resonance and petrographic analysis for dating Mesolithic and Neolithic pottery from Al Khiday (Sudan)

Abstract Electron Paramagnetic Resonance (EPR) dating, like luminescence techniques, is based on the time-dependent accumulation of trapped charges at mineral defect centres. However, Fe(III) ions prevent the common Continuous Wave (CW-EPR) approach for dating pottery, which always contains iron. The Pulsed method (ED-EPR) allowed this limitation to be overcome, with recording of radiation-induced defect signals, as shown by increased signal intensity after artificial irradiation of samples. The method was applied to studying Mesolithic and Neolithic pottery from Al Khiday (Central Sudan), characterized by quartz-rich tempers and coming from dated contexts. As the occurrence of a natural ED…

Testing and calibration of ESR response of Fricke gel dosimeters in mixed neutron-gamma fields

Compositi elettroattivi costituiti da nanoparticelle di polianilina disperse in polivinilpirrolidone

EPR/ALANINE PELLETS WITH LOW Gd CONTENT FOR NEUTRON DOSIMETRY

This paper reports on results obtained by electron paramagnetic resonance (EPR) measurements and Monte Carlo (MC) simulation on a blend of alanine added with low content of gadolinium oxide (5 % by weight) to improve the sensitivity to thermal neutron without excessively affecting tissue equivalence. The sensitivity is enhanced by this doping procedure of more an order of magnitude. The results are compared with those obtained with the addition of boric acid (50 % by weight) where boron is in its natural isotopic composition in order to produce low-cost EPR dosemeters. The gadolinium addition influences neutron sensitivity more than the boron addition. The presence of additives does not sub…

DOSIMETRIA DI FASCI NEUTRONICI TRAMITE SPETTROSCOPIA DI RISONANZA PARAMAGNETICA ELETTRONICA (EPR)

Studio di fattibilità sull’applicazione della tecnologia delle radiazioni ionizzanti al trattamento delle acque reflue in Sicilia. Quaderno N. 3/2007, Dipartimento di Ingegneria Nucleare, Università degli Studi di Palermo.

Progettazione di un irradiatore autocontenuto per la calibrazione di dosimetri personali a termoluminescenza

I dosimetri a termoluminescenza utilizzati nel campo della dosimetria personale necessitano – per un loro corretto impiego - di una preventiva fase di calibrazione, realizzata con dose-rate compresi tra 2,5 10-4 mGy/h e 0,01 mGy/h. Per ottenere valori di dose-rate in tale range, si è progettato un irradiatore autocontenuto e autoschermato di piccole dimensioni, utilizzante una sorgente di bassa attività.

Studio di fattibilità di un impianto E-Beam per il trattamento dei reflui civili dell’impianto di Acqua dei Corsari a Palermo

Investigation on the ganaration process of HO2• radicals by γ-ray irradiation in O2-loaded fumed silica

Abstract We report an experimental investigation on the effects of γ-ray irradiation in three types of fumed silica previously loaded with O 2 molecules. Our data indicate that the main effect of irradiation in these systems is to generate a very large concentration of HO 2 interstitial radicals (about 10 18  molecules/cm 3 ). Furthermore, the number of generated HO 2 was found to be larger in the samples with higher O 2 contents before irradiation. This correlation suggests that HO 2 radicals are induced by reaction of interstitial O 2 molecules with radiolytic H atoms, as previously suggested for O 2 -loaded bulk amorphous silicon dioxide (a-SiO 2 or silica) samples. However, at variance …

Response of GAFChromic® HD-V2 film dosimeter in 10-300 Gy dose range for radiation testing of electronic devices

The study reported in this paper aimed to investigate the response of a GAFChromic? HD-V2 film dosimeter in the dose range between 10 and 300 Gy, normally used to perform irradiation tests on electronic devices with a 60Co gamma-ray irradiator. The well-defined linearity of response in terms of absorbance as a function of absorbed dose, easiness of handling and data analysis of irradiated dosimeters, reproducibility, stability, and insensitivity to visible light and most of the environmental parameters, make HD-V2 film a flexible, inexpensive and reliable dose measurement device. The study has shown a fogging effect of the dosimeter response since its value changes over time. Strategies and…

Una stazione per il monitoraggio on-line di radioattività atmosferica: criteri di progetto e valutazione dei costi

Presso la Sezione di Ingegneria Nucleare del Dipartimento dell’Energia (già Dipartimento di Ingegneria Nucleare, DIN) dell’Università di Palermo, è installato un sistema di aspirazione di particolato atmosferico ad altissimo volume (circa 1000 m3/h di aria). Costruito agli inizi degli anni ottanta del secolo scorso, risulta ormai datato in parte della strumentazione a corredo oltre che nella stessa struttura di protezione dagli agenti atmosferici che lo contiene. La stazione di prelievo è stata utilizzata fino a qualche anno addietro per il monitoraggio giornaliero di deboli concentrazioni di inquinanti radioattivi in aria, con livelli di Minima Attività Rivelabile (MAR) abbastanza ridotti …

The gas chromatography/mass spectrometry can be used for dose estimation in irradiated pork

Abstract Food safety can be improved using ionizing radiation to reduce food spoilage and to extend its shelf life. The gas chromatography/mass spectrometry (GC/MS) has been validated by the European Community as a powerful method to identify irradiated food containing fat. The preliminary goals of our research were: (i) to set up this method, based on the detection of radiation induced 2-dodecylcyclobutanones (2-DCB) in pork muscle samples and (ii) to check the microbiological efficacy of the treatment. The main objective was to render the GC/MS a quantitative technique for dose estimation, through the measurement of the 2-DCB concentration in the irradiated sample. Our results show that t…

Generation of oxygen deficient point defects in silica by γ and β irradiation

We report an experimental study of the effects of y and β irradiation on the generation of a point defect known as ODC(II) in various types of commercial silica (a-SiO 2 ). The ODC(II) has been detected by means of photoluminescence (PL) spectroscopy measuring the PL band centered at 4.4 eV and excited at 5.0 eV associated to this defect. Our experiments show that ODC(II) are induced in all the investigated materials after irradiation at doses higher than 5 x 10 2 kGy. A good agreement is observed between the efficiencies of generation of ODC(II) under y and β irradiation, enabling a comprehensive study up to the dose of 5 x 10 6 kGy. Two different growth rates, one in the low and one in th…

Characterization of Fricke gel dosimeters exposed to gamma rays and neutrons

Electric properties of gamma-crosslinked hydrogels incorporating organic conducting polymers

Neutron dosimetry by means of electron spin resonance (ESR) tecnique

Along with the Neutron Capture Therapy (NCT) development and with the use of thermal neutrons for radiotherapeutic purposes, many efforts have been devoted to the beam characterization in order to optimize the therapy procedures. Reliable dosimetric measurements should be able to determine the various components (neutronic and photonic) of the mixed beam usually employed for therapy. We have studied the effect of the additive such as gadolinium and 10B-boric acid on the neutron sensitivity of alanine ESR dosimeters exposed to a gamma and mixed (n, gamma) field mainly composed by thermal neutrons. We have chosen both this additive nuclei because of their very high capture cross section to th…

Electrically conductive hydrogel composites made of polyaniline nanoparticles and poly(N-vinyl-2 pyrrolidone)

Effect of oxygen deficiency on the radiation sensitivity of sol-gel Ge-doped amorphous SiO2

We report experimental investigation by electron paramagnetic resonance (EPR) measurements of room temperature γ-ray irradiation effects in sol-gel Ge doped amorphous SiO2. We used materials with Ge content from 10 up to 104 part per million (ppm) mol obtained with different preparations. These latter gave rise to samples characterized by different extents of oxygen deficiency, estimated from the absorption band at ~5.15 eV of the Ge oxygen deficient centers (GeODC(II)). The irradiation at doses up to ~400 kGy induces the E'-Ge, Ge(1) and Ge(2) paramagnetic centers around g ~ 2 with concentrations depending on Ge and on GeODC(II) content. We found correlation between Ge(2) and GeODC(II) con…

APPLICAZIONE E SVILUPPO DI UN METODO DI IDENTIFICAZIONE DEI MANGIMI IRRADIATI E VALUTAZIONE DELLA CAPACITA' SANITIZZANTE DEL TRATTAMENTO RADIANTE

Properties of HO2• radicals induced by γ-ray irradiation in silica nanoparticles

Abstract We report an experimental investigation on the effects of γ -ray irradiation in several types of silica nanoparticles previously loaded with O 2 molecules. They differ in specific surface and average diameter. By electron paramagnetic resonance (EPR) measurements we observe the generation of about 10 18 HO 2 • /cm 3 interstitial radicals. These radicals are induced by reaction of interstitial O 2 molecules with radiolytic H atoms, as previously suggested for O 2 -loaded bulk a-SiO 2 samples. However, at variance with respect to bulk materials, our experimental evidences suggest a different generation process of HO 2 • radical. In fact, by a detailed study of samples exposed to D 2 …

Silicon dosimeters based on Floating Gate Sensor: design, implementation and characterization

A rad-hard monolithic dosimeter has been implemented and characterized in a standard 180 nm CMOS technology. The radiation sensor (C-sensor) is based on a Floating Gate (FG) MOS discharge principle. The output current is processed by a current-to-voltage (I/V) interface and then converted by a 5-bit flash ADC. The dosimeter is re-usable (FG can be recharged) and can detect a dose up to 1krad (Si) with a resolution of 30rad (Si) typical over temperature 0 to 85°C range. The ADC allows easy further signal processing for calibration and averaging, etc. The power consumption of C-sensor plus I/V interface is < 2mW from a 5 V power supply. The overall layout area is less than 0.25mm2. The Rad…

Valutazione della fluenza di neutroni di origine cosmica a livello del suolo

Lo studio degli effetti delle radiazioni neutroniche sul funzionamento dei componenti che fanno parte dei più comuni sistemi elettronici comporta lo studio della fluenza neutronica di origine cosmica a livello del suolo. Infatti la sorgente primaria dei neutroni in atmosfera è principalmente individuabile nell’interazione tra i raggi cosmici di origine solare ed i vari strati dell’atmosfera. Il campo neutronico pertanto non è dunque costante ma dipende fortemente dai cicli di attività solare. In questo lavoro sono presentati i risultati di due cicli di misurazioni del “dose rate” da neutroni nei periodi 21-28 Febbraio e 29 Febbraio-7 Marzo 2012. La strumentazione utilizzata è costituita dal…

Dosimetria a risonanza di spin elettronico (ESR) tramite composti organici (alanina e tartrato di ammonio) per campi misti neutroni-gamma

The influence of the processing temperature on gamma curing of epoxy resins for advanced composites

Radiation curing of an epoxy resin based system under controlled temperature conditions

Qualitative and quantitative thermoluminescence analysis on irradiated oregano

Abstract Thermoluminescence (TL) dosimetry is one of the physical methods used for the identification of irradiated food, suitable for foods from which silicate minerals can be extracted. The aims of the present work were to apply the TL analysis for a qualitative identification of irradiated oregano, and to set up a quantitative procedure to estimate the original treatment dose on the sample. The experimental results show that the TL analysis allows to distinguish irradiated oregano even seven months after the treatment. The additive dose procedure gives a rough estimation of the treatment dose, but can be helpful when the TL ratio method is unsatisfactory.

I fenoli come nuovi materiali per la dosimetria EPR in campo misto neutroni-gamma

Applicazione della spettroscopia ESR per la ricostruzione della dose in ossa di pollo irradiato a scopo conservativo

Neutron ESR dosimetry through ammonium tartrate with low Gd content.

This paper continues analyses on organic compounds for application in neutron dosimetry performed through electron spin resonance (ESR). Here, the authors present the results obtained by ESR measurements of a blend of ammonium tartrate dosemeters and gadolinium oxide (5 % by weight). The choice of low amount of Gd is due to the need of improving neutron sensitivity while not significantly influencing tissue equivalence. A study of the effect of gadolinium presence on tissue equivalence was carried out. The experiments show that the neutron sensitivity is enhanced by more than an order of magnitude even with this small additive content. Monte Carlo simulations on the increment of energy rele…

Thermoluminescence detection of irradiated crustaceans: comparison between two methods for extracting minerals

Dangerous effects induced on power MOSFETs by terrestrial neutrons: A theoretical study and an empirical approach based on accelerated experimental analysis

This paper investigates the effects that terrestrial neutrons can induce on power MOSFETs when they are biased during their normal working conditions especially in inverters for photovoltaic applications. After a brief review of power MOSFETs failure phenomena caused by neutron irradiation (with emphasis on so called “Single Event Effects” (SEE)), the results of an accelerated test performed with the Am-Be source at the University of Palermo are discussed.

Radiation induced generation of Non-Bridging Oxygen Hole Center: intrinsic and extrinsic processes

Dosimetria ESR per la identificazione di frutta secca irradiata e stima della dose

DOSE RECOSTRUCTION IN IRRADIATED FOOD CONTAINING HYDROXIAPATITE USING ESR SPECTROMETRY

MISURE SPETTROMETRICHE GAMMA DI IMPUREZZE RADIONUCLIDICHE IN PRODOTTI RADIOFARMACEUTICI IMPIEGATI IN MEDICINA NUCLEARE

La recente approvazione e pubblicazione dell’edizione aggiornata della Farmacopea ufficiale (Decreto del 30 marzo 2005) e l’introduzione di requisiti di purezza dei radiofarmaci, ha condotto a sviluppare una serie di studi e di metodiche per la verifica della purezza radionuclidica di un prodotto radioafarmaceutico. Le Norme di buona preparazione di radiofarmaci in Medicina Nucleare individuano alcune procedure di accertamento e di garanzia della qualità di un prodotto tramite l’impiego di una serie di prove predisposte per valutare parametri fisici, chimici, biologici essenziali per la somministrazione in sicurezza a pazienti. La purezza radionuclidica del radiofarmaco è solitamente valuta…

GAS CHROMATOGRAPHIC/MASS SPECTROMETRIC AND MICROBIOLOGICAL ANALYSISES ON IRRADIATED CHICKEN

Study of the response of phenol compounds exposed to gamma photons and neutrons for Electron Spin Resonance dosimetry

Application of the ESR spectrometry to evaluate the original dose in irradiated dried fruit

The identification of irradiated dried fruit can be achieved by means of the electron spin resonance (ESR) spectrometry, as recommended by the European Community, since ionizing radiation induces free radicals in cellulose, a constituent of the shell. The aim of this work was to use the ESR spectrometry also as a quantitative procedure to evaluate the original dose in irradiated dried fruits, using the additive dose method. Little shell pieces, taken from nuts, chestnuts, peanuts and pistachios, were irradiated at “original” dose values in the range 1 to 8 kGy, and the ESR signal intensity was measured. Each specimen was then reirradiated with added doses of 1 kGy, and the ESR signal was me…

Concentration growth and thermal stability of gamma-ray induced germanium lone pair center in Ge-doped sol–gel a-SiO2

Abstract We report an experimental study of the concentration growth by γ-ray irradiation of germanium lone pair center (GLPC) in 10 4 part per million molar Ge-doped sol–gel silica. The data show that γ-ray induced GLPC concentration increases linearly up to ∼5 MGy and then it seems to reach a limit value. In addition to the dose dependence, we have studied the thermal stability of the radiation induced GLPC in ambient atmosphere up to 415 °C. We found that the concentration of this latter GLPC starts to decrease at ∼300 °C, at variance to native GLPC, suggesting that the annealing is related to irradiation products. After the thermal treatments the photoluminescence (PL) activity of the γ…

EPR dating of shells from Malhada Marsh, Rio de Janeiro, Brazil

The formation of the coastal plain of the Brazilian sea is mainly due to the fluctuation of relative sea level in the past. Armacao dos Buzios or simply Buzios is a municipality in the microregion of lakes, in the state of Rio de Janeiro. In this region there is a lowland area about two meters above current sea level. This lowland area is also known as coastal plain of Una River. It is expected that during the Holocene period the sea level reached a maximum about 2.5 meters above the current level. During that time billions of mollusks lived and proliferated in the shallow waters around the coastal plain of the Una River. As they died their shells formed a layer in the soil including Malhad…

Polymer matrices for composites obtained through radiation curing of epoxy resins

Concentration growth and thermal stability of gamma-ray induced Germanium lone pair center in Ge-doped sol-gel SiO2

ESR response of phenol compounds for dosimetry of gamma photon beams

Abstract In the present paper we investigate the features of IRGANOX® 1076 phenols as a material for electron spin resonance (ESR) dosimetry. We experimentally analyzed the ESR response of pellets of IRGANOX® 1076 phenols irradiated with 60Co photons. The best experimental parameters (modulation amplitude and microwave power) for dosimetric applications have been obtained. The dependence of ESR signal as function of γ dose is found to be linear in the dose range studied (12–60 Gy) and the lowest measurable dose is found to be of the order of 1 Gy. The signal after irradiation is very stable in the first thirty days. From the point of view of the tissue equivalence, these materials have mass…

ISO 14470:2011 and EU legislative background on food irradiation technology: The Italian attitude

Our work aim is to produce an overview of food irradiation technology at European Union level, with a focus on the Italian context, by specifying the legislative background, detection methods and labelling obligations. We highlight how consumers are too often misinformed about this technology and its benefits. For this purpose, a series of tools aimed at improving the amount of information have been proposed, allowing the consumer to make a free choice about whether or not to buy irradiated food based on the correct information received, independent from socio-economic factors. Finally, we show the common effort at EU and International level, represented by the ISO 14470:2011 quality standa…

Ionizing radiation induced curing of epoxy resin based systems for advanced composites matrices

Design and realization of a radon chamber as a secondary standard

The air-radon mixture is the most significant source of natural radiation in workplaces and within dwellings. Despite some uncertainty in the risk estimates, it is widely believed that greater the exposure to radon, greater the risk of developing lung cancer. To assess the radiological hazard, accurate measurements of radon concentrations are necessary. A large variety of radon monitoring instruments have been developed in the last years, usually calibrated in radon chambers containing a known radon concentration released within the chamber by a specific solid radium-226 source. Radon calibration chamber has been constructed to test and calibrate radon and radon progeny detectors at various…

The influence of the processing temperature on gamma curing of epoxy resins for the production of advanced composites

Abstract Gamma radiation curing of an epoxy monomer, in the presence of an iodonium salt, as initiator, is studied. Systems have been polymerized at the same irradiation dose and dose rate and at different processing temperatures. The experimental results show that all the irradiated materials exhibit a latent reactivity, undergoing toward an increase of crosslinking density if they are thermally cured after irradiation. The results indicate that the processing temperature affects both the crosslinking density after irradiation and the sensibility to the post-irradiation thermal treatment.

Study of the response of phenol compounds exposed to thermal neutrons beams for Electron Paramagnetic Resonance dosimetry

Abstract This paper reports the results regarding a new organic compound (IRGANOX ® 1076 phenols) with and without low content (5% by weight) of gadolinium oxide (Gd 2 O 3 ) for Electron Paramagnetic Resonance (EPR) dosimetry of neutron beams. The dependence of EPR signal as function of neutron dose was investigated in the fluence range studied between 10 11  cm −2 to 10 14  cm −2 . We evaluated also the effect of gadolinium on 60 Co gamma photon sensitivity of this organic compound. Our analysis showed that a low concentration of gadolinium oxide (of the order of 5% of the total mass of the dosimeter) can enhance the thermal neutron sensitivity more than 10 times with a small reduction of …

Studio e calibrazione della risposta ottica ed NMR di dosimetri gel di tipo Fricke (FXG) in campi misti neutroni-gamma per applicazioni cliniche

Experiences of radioactivity measurement in various environmental samples

An overview on our activity of environmental radioactivity measurement is reported. Radionuclide concentration have been evaluated in the particulate air, soils and rocks, drinking and surface water, wastewater, marine sediments and so on. Most of radionuclide concentration evaluation were performed using facilities of DEIM Department of Palermo University. In particular, particulate collection was performed by suction of atmospheric air through 45x45 Sofiltra-Poelman HYN-75 (Bleu type) cellulose filter paper using a high-volume air sampler located on the roof of our department building (20 m above ground-level), located within an undisturbed large park area in the city of Palermo (latitude…

Gas chromatographic/mass spectrometric and microbiological analyses on irradiated chiken

Ionizing radiation is widely used as treatment technique for food preservation. It involves among others reduction of microbial contamination, disinfestations, sprout inhibition and extension of shelf life of food. However, the commercialization of irradiated food requires the availability of reliable methods to identify irradiated foodstuffs. In this paper, we present results on the application to irradiated chicken of this method, based on the detection, in muscle and skin samples, of the peaks of ions 98 Da and 112 Da, in a ratio approximately 4:1, typical of radiation induced 2-dodecylcyclobutanones (2-DCB). Aim of the work was also to study the time stability of the measured parameters…

APPLICATION OF THE ESR SPECTROMETRY TO EVALUATE THE ORIGINAL DOSE IN IRRADIATED FOOD CONTAINING HYDROXIAPATITE

Evaluation of the original dose in irradiated dried fruit by ESR spectroscopy

Neutron and gamma-ray radiation fields characterisation in a 241Am–Be irradiator in view of its use as research testing tool

Abstract A neutron irradiation facility based on four 241Am–Be sources, each one with an activity of 111 GBq, placed in Plexiglas pipes inside a tank filled with water used both as a moderator and a biological shielding, has been realized at the Engineering Department of Palermo University. In view of its use as a testing tool in various research activities, a characterisation of the irradiator has been carried out through the determination of neutron and gamma-ray flux profiles, the evaluation of the thermal to total neutron flux percentage ratio and of the epithermal neutron shaping factor. To this aim, results of a Monte Carlo (MCNP5 code) simulation based on a previously validated sourc…

DOPED ALANINE ESR DOSIMETERS FOR MEASUREMENTS OF THERMAL NEUTRON FLUENCE IN A MIXED RADIATION FIELD

IDENTIFICAZIONE CON GC/MS E INDAGINE MICROBIOLOGICA DI POLLO IRRADIATO

DOSE RECONSTRUCTION IN IRRADIATED OREGANO BY THERMOLUMINESCENCE DOSIMETRY

Education and Research in Nuclear Engineering and Radiological Protection at Nuclear Engineering Department of Palermo University

Room Temperature Instability of E′γ Centers Induced by γ Irradiation in Amorphous SiO2

We study by optical absorption measurements the stability of E'(gamma) centers induced in amorphous silica at room temperature by gamma irradiation up to 79 kGy. A significant portion of the defects spontaneously decay after the end of irradiation, thus allowing the partial recovery of the transparency loss initially induced by irradiation. The decay kinetics observed after gamma irradiation with a 0.6 kGy dose closely resembles that measured after exposure to 2000 pulses of pulsed ultraviolet (4.7 eV) laser light of 40 mJ/cm(2) energy density per pulse. In this regime, annealing is ascribed to the reaction of the induced E'(gamma) centers with diffusing H(2) of radiolytic origin. At higher…

EVALUATION OF GAMMA-RAY AND NEUTRON FLUXES IN A NEUTRON IRRADIATOR USED FOR RAD-HARD ELECTRONIC COMPONENTS TESTING

An irradiator with four Am-Be neutron sources (activity 111 GBq each) was used for testing electronic RAD-HARD components developed for space application [1]. For this goal, an essential requirement to be met is the knowledge with sufficient precision of neutron and gamma-ray fluxes in the irradiation channel where the components are put for the test. For this goal, an experimental measurement activity was started to validate also Monte Carlo simulation results, obtained with application of MCNP5 code. As regards gamma-ray flux, we considered separately two gamma-ray contributions: the first one, at 60 keV energy, associated with the decay of the 241Am, and the second one, at 2.2 MeV, due t…

Refractive index change dependence on Ge(1) defects inγ-irradiated Ge-doped silica

We present an experimental study regarding the effects of the $\ensuremath{\gamma}$ radiation on silica glass doped with Ge up to $10\text{ }000$ ppm molar produced by the sol-gel technique. We have determined the irradiation-induced changes in the refractive index $(\ensuremath{\Delta}n)$ as a function of the oxygen deficiency of the samples, evaluated from the ratio between the germanium lone pair centers (GLPC) and the Ge content. $\ensuremath{\Delta}n$ at 1500 nm have been estimated using optical-absorption spectra in the range 1.5--6 eV. We have found that $\ensuremath{\Delta}n$ is independent of Ge differences for GLPC/Ge values $l{10}^{\ensuremath{-}4}$, while it depends on Ge for la…

Procedura di calibrazione di un set di Dosimetri TLD secondo la ISO/ASTM51956:2005(E) e la ASTM standard E-668

La misura della dose assorbita da dosimetri passivi, a seguito della loro esposizione a radiazioni ionizzanti, è una procedura fondamentale per valutare gli effetti indotti da tali radiazioni nell’ambito della dosimetria ambientale. Per effettuare delle corrette valutazioni, è stato selezionato un set di dosimetri a termoluminescenza (TLD) scelti, tra un’ampia gamma di tipologie di dosimetri a nostra disposizione, come i più idonei a fornire misure di dose attendibili (nelle prescritte condizioni di funzionamento). Tali dosimetri sono stati sottoposti ad una specifica procedura di irraggiamento e successiva lettura, allo scopo di realizzare un’opportuna calibrazione nel rispetto di quanto p…

Sintesi di materiali avanzati mediante radiazioni ionizzanti

Fogging effect correction of Gafchromic HD-V2 film response for its use in high-dose radiotherapy

GAFChromic® HD-V2 film is a reliable dose measurement device, thin, flexible, inexpensive, simple to use and easy to analyze. The response in terms of net absorbance with respect to absorbed dose was found to be linear in a large dose range, which supports the feasibility of using the film dosimeters in many applications, such as radiotherapy. For its use, a "fogging" effect must be take into account since film response changes with time. To determine a calibration curve valid for any time, fogging effect was investigated for more than 400 days. A correction procedure allows the use of HD-V2 film dosimeters in high-dose radiotheraphy, as brachytherapy, and quality assurance (QA) procedures.

UN IRRADIATORE NEUTRONICO MODULARE CON SORGENTI DI 241Am-Be PER IL TEST DI DOSIMETRI NEUTRONICI PERSONALI

Irradiatori neutronici basati su sorgenti radionuclidiche sono impiegati in diversi paesi per l’analisi per attivazione di vari campioni, per studiare le caratteristiche dei materiali sottoposti a irradiazione, ma anche per studiare la risposta di rivelatori e/o dosimetri personali sensibili alla componente neutronica. Per quest’ultima applicazione, l’uso di un irradiatore con sorgenti risulta molto vantaggioso per la stabilità nel tempo del flusso neutronico, mentre è relativamente poco importante il valore assoluto del flusso neutronico, di qualche ordine di grandezza inferiore a quello di reattori o di acceleratori di particelle. Per l’effettuazione di test su rivelatori e/o dosimetri pe…

centers induced by γ irradiation in sol–gel synthesized oxygen deficient amorphous silicon dioxide

The effects of room temperature γ-ray irradiation up to a dose of ∼1300 kGy are investigated by Electron paramagnetic resonance (EPR) measurements in amorphous silicon dioxide (a-SiO2) produced by a sol-gel synthesis method that introduces O{triple bond, long}Si{single bond}Si{triple bond, long}O oxygen deficiency. We have found that exposure to radiation generates the Eγ′ center with the same spectral features found in high purity commercial a-SiO2. The maximum concentration of defects induced in this sol-gel material indicates that its resistance to radiation is comparable to that of synthetic fused a-SiO2. The concentration of Eγ′ center increases with irradiation, featuring a sublinear …

Valutazione sperimentale delle componenti del campo di radiazioni in un irradiatore neutronico con sorgenti 241Am-Be e confronto con simulazioni Monte Carlo

Il presente lavoro riguarda la valutazione sperimentale delle componenti gamma e neutronica del campo di radiazioni presente in diversi punti all’interno del canale di irraggiamento di un irradiatore neutronico con sorgenti 241Am-Be. Per la componente gamma sono stati considerati due contributi: il primo associato a gamma di energia di 60 keV, dovuto al decadimento dell'241Am; il secondo a gamma di energia 2,2 MeV, dovuto alla cattura radiativa dei neutroni da parte dello schermo biologico (acqua) che circonda le sorgenti. Per le misure sperimentali sono stati utilizzati dosimetri tipo TLD700 in due diverse configurazioni: TLD "nudi" per misura della dose relativa al campo gamma totale e TL…

Ionizing radiation induced curing of epoxy resin for advanced composites matrices

Abstract The radiation curing of an epoxy monomer in the presence of an iodonium salt, as photo initiator, is studied. Systems with different concentrations of photo initiators have been polymerized via both gamma rays and e-beam, at various dose rates. The aim of this work is to investigate how the photo initiator concentration and the irradiation dose rate affect the temperature of the systems during curing and how the different thermal histories influence the dynamic mechanical thermal properties of the obtained materials.

Progettazione e realizzazione di un irradiatore neutronico modulare basato su sorgenti Am-Be

Irradiatori neutronici basati su sorgenti radionuclidiche sono impiegati in diversi paesi per studiare le caratteristiche dei materiali sottoposti a irradiazione e/o la risposta di rivelatori e/o dosimetri personali sensibili alla componente neutronica. Per quest’ultima applicazione, l’uso di un irradiatore con sorgenti radionuclidiche risulta molto vantaggioso per la stabilità nel tempo del flusso neutronico, mentre è relativamente poco importante il valore assoluto del flusso neutronico, che può anche essere di qualche ordine di grandezza inferiore a quello di reattori o di acceleratori di particelle. Per l’effettuazione di test su rivelatori e/o dosimetri personali neutronici risulta mol…

Electron paramagnetic resonance investigation on the hyperfine structure of the center in amorphous silicon dioxide

Abstract We report an experimental investigation by electron paramagnetic resonance (EPR) spectroscopy on the hyperfine structure of the E δ ′ center in γ-ray irradiated amorphous silicon dioxide materials. This study has driven us to the determination of the intensity ratio between the hyperfine doublet and the main resonance line of this point defect. This ratio was obtained for a variety of silica samples and compared with the analogous ratio obtained for the E γ ′ defect. The comparison definitively confirms that the electronic wave function involved in the E δ ′ center is actually delocalized over four nearly equivalent Si atoms.

Caratterizzazione ESR di composti fenolici: nuovi materiali per la dosimetria in campo misto neutroni-gamma

La camera Radon del Dipartimento di ingegneria Nucleare dell'Università di Palermo

A chamber to test the response of radon detectors to changing environmental conditions.

Radon risk assessment is carried out with accurate measurements with active or passive instrumentation. All radon detectors must be calibrated and tested using a radon chamber containing a known concentration of radon produced by specific sources of 226Ra. Some of the chambers can also be used to test the response of detectors as a function of environmental conditions. In this case, it can be inferred a calibration curve with respect to changing of the parameter considered. For this aim, a new chamber radon was designed and realized to perform both calibration of instruments and to study the detector response in a large range of variation of the environmental parameters (pressure, 700 - 110…

Electron paramagnetic resonance line shape investigation of the Si-29 hyperfine doublet of the E'γ center in a-SiO2

We report an experimental study by electron paramagnetic resonance (EPR) spectroscopy of the E′γ center and of its hyperfine structure, consisting in a pair of lines split by 42 mT. Our results show that two types of E′γ centers can be distinguished on the basis of the EPR line shapes of their main resonance line and hyperfine structure. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Uno studio per l’implementazione della strumentazione della stazione di prelievo di particolato atmosferico del DIN di Palermo

Dangerous Effects Induced on Power MOSFETs by Terrestrial Neutrons

This paper investigates the effects that terrestrial neutrons can induce on power MOSFETs when they are biased during their normal working conditions especially in inverters for photovoltaic applications. After a brief review of power MOSFETs failure phenomena caused by neutron irradiation (with emphasis on so called “Single Event Effects” (SEE)), the results of an accelerated test performed with the Am-Be source at the University of Palermo are discussed.

Effetto della distribuzione della densità di potenza sulle analisi della composizione finale del combustibile di un PWR effettuate con Origen2

Previsione, mediante codice di calcolo, della composizione finale del combustibile utilizzato in un reattore tipo PWR, in relazione al suo tempo di funzionamento ed alla densità di potenza impiegata.

Epoxy resin based matrices for advanced composites cured by ionizing radiation. Study of the influence of process parameters on final properties

Attivita’ di misura delle concentrazioni di radionuclidi naturali gamma-emittenti nel particolato atmosferico a Palermo

Piani di Sicurezza per il trasferimento di sorgenti di radiazioni gamma e neutroni ad alta attività

La movimentazione di sorgenti ad alta attività, sia che si tratti dell’acquisizione, trasporto e collocazione di nuove sorgenti in impianti di irraggiamento, o del trasferimento di sorgenti all’interno della stessa struttura, deve essere pianificata nei minimi dettagli con un piano di lavoro. Ciò è fondamentale per l’analisi di tipo radioprotezionistico ma anche dal punto di vista della valutazione dei rischi di altra natura, non ultima la movimentazione dei carichi. Tale analisi preventiva viene effettuata avvalendosi sinergicamente di un gruppo di esperti con diverse competenze e varie figure di responsabilità (Responsabile delle sorgenti, RSPP, Esperto Qualificato, Medico Autorizzato, …)…

Le facilities di irraggiamento del DEIM per il testing di componenti rad-hard

Il Dipartimento Energia, Ingegneria dell’Informazione e Modelli Matematici dell’Università degli Studi di Palermo (DEIM), ospita due facility di irraggiamento impiegate per attività di didattica, sperimentale e di ricerca: • Impianto di irraggiamento Gamma Sicilia 3 (IGS-3); Irradiatore neutronico Am-Be. In questa monografia sono presentate le caratteristiche dei due impianti di irraggiamento insieme alle proprietà di interazione delle radiazioni con la materia, con particolare riferimento agli effetti sui componenti elettronici.

Application of the ESR spectroscopy to estimate the original dose in irradiated chicken bone

Abstract The paper discusses the results of an investigation aimed to use the ESR spectroscopy as a quantitative procedure to estimate the original dose in irradiated chicken. The time stability of the ESR signal was at first carried out, to obtain a correction factor to be applied to the dose estimated with the added dose method. Our results show that this procedure gives an estimation of the original dose within ±25%.

Phenol compounds for Electron Spin Resonance dosimetry of gamma and neutron beams

E’_gamma centers induced by gamma irradiation in sol-gel synthesized oxygen deficient amorphous silicon dioxide.

Ottimizzazione della dosimetria a termoluminescenza per la identificazione di spezie ed erbe aromatiche irradiate

The methodology for active testing of electronic devices under the radiations

The methodology, developed for active testing of electronic devices under the radiations, is presented. The test set-up includes a gamma-ray facility, the hardware board/fixtures and the software tools purposely designed and realized. The methodology is so wide-ranging to allow us the verification of different classes of electronic devices, even if only application examples for static random access memory modules are reported.

Radiation induced generation of non-bridging oxygen hole center in silica: Intrinsic and extrinsic processes

Abstract The generation of non-bridging oxygen hole center ( Si–O ) was investigated in a wide variety of natural (fused quartz) and synthetic silica samples exposed to different γ- and β-irradiation doses by looking at its optical bands. We distinguish two different generation processes: intrinsic associated with the cleavage of Si–O bond and characterized by a sublinear law and extrinsic due to the conversion of OH precursor characterized by a growth curve with a saturating tendency. The interplay between the two processes and the role of H are discussed.