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C Furetta

Publications and source records attributed to C Furetta.

At least 19 recordsLinked to original sources

Comparison of the TL responses of two different preparations of LiF:Mg,Cu,P irradiated by photons of various energies.

The aim of this work is to present the results concerning the photon irradiation of a new phosphor, the LiF:Mg,Cu,P+PTFE, produced at the Instituto Nacional de Investigaciones Nucleares (ININ-Mexico). The photon irradiations were performed using X-rays of 16, 24, 34.5, 42, 100 and 145keV, and gamma rays from (137)Cs (662keV) and from (60)Co (1 252keV). The results obtained are normalized to the (60)Co response. The experimental data are then compared to those obtained using the commercial dosimeters TLD-100 and GR-200A.

Copper↗

Kinetic study of the thermoluminescence of KMgF3:LaF3 compounds employing the general one trap model.

The parameters characterising the trap centres involved in the thermoluminescence of KMgF3:LaF3 compounds have been found by deconvolving the glow curve with the General One Trap model (GOT). For the fitting procedure the Levenberg-Marquardt method has been employed. Tm-T(stop) measurements along with initial rise measurements were performed in order to estimate the number of peaks the glow curve is made up of, and the corresponding activation energies. Instead of the Runge-Kutta method, a novel algorithm has been employed to integrate the differential equation of the GOT model, which reduces the computational time nearly 30 times with respect to the former when the glow curve is recorded with a lineal heating rate profile. The strong computational time reduction makes feasible a large number of runs with different guess values. An interesting result is that the concentration of disconnected deep traps is much less than the concentration of trap centres.

Computer Simulation↗

Simple methods to analyse thermoluminescence glow curves assuming arbitrary recombination-retrapping rates.

Numerical solutions of the differential equations system describing the transitions between energy levels can help in the understanding of the physical mechanisms governing thermoluminescence (TL) emission but they are not suitable for the analysis of complex experimental TL glow curves. On the other hand, simplified descriptions, as mixed or general order kinetics, require many additional assumptions that may limit the validity of the results or are mostly empirical. In this paper, the accuracy of such approximations has been evaluated for different retrapping-recombination ratios and it has been found that differences between the fitted and the simulated parameters arise from the simplification of the models because quasi-equilibrium condition seems to be valid in all the considered cases.

Algorithms↗

Thermoluminescence properties of Chile Guajillo paprika Mexicano.

The thermoluminescence properties of the inorganic dust extracted from the Chile Guajillo (paprika) Mexicano, were studied in order to verify the possibility of using the TL technique to discriminate between irradiated and non irradiated peppers. The inorganic dust was found to consist of quartz 60%, albite (NaAlSi(3)O(8)) 30%, and ortose (KAlSi(3)O(8)) 10%. Its thermoluminescence dose response covers the wide dose range of 1 Gy--10 kGy, which was attributed mainly to feldspars. Its high sensitivity and its stability over 10 irradiation-readout cycles allow the application of a single grain--single aliquot regeneration dosimetry in Chile Guajillo (paprika). Evaluations based on trapping parameters show that thermal fading at room temperature for glow-peaks above 180 degrees C, is not a problem in the dosimetry of paprika.

Capsicum↗

Optically and thermally stimulated luminescence of KMgF3:Ce3 and NaMgF3:Ce3+.

The potentialities of optically stimulated luminescence (OSL) for personal dosimetry of ionising radiation have stimulated the search for new synthetic materials with good dosimetric properties. The sensitivity of two new OSL materials KMgF3 and NaMgF3 doped with Ce3+ ions has been evaluated and found to be of the same order of magnitude as that of Al2O3:C. Several other characteristics have also been investigated. Promising results for KMgF3:Ce are the high sensitivity and the low fading. However, this material suffers from a high self-dose due to the presence of 40K. NaMgF5:Ce is sensitive as well but shows strong fading. Interesting information on the mechanism has been obtained by correlating the signals of OSL and TL. Furthermore, the different bleachabilities under blue LED illumination of the strongly overlapping glow peaks allowed the extraction of one single peak for KMgF3:Ce3+. The results demonstrate new possibilities offered by the combination of TL and OSL.

Cerium↗

Thermoluminescence properties of LiMgF3 doped with Ce, Er and Dy.

The main dosimetric properties are reported of a new perovskite, LiMgF3, doped with Ce, Er and Dy impurities. An annealing temperature of 400 degrees C for one hour is necessary to erase any previous signal and to stabilise its sensitivity. A readout up to 450 degrees C gives the same result. The glow curve structure consists of two intense and isolated glow peaks at 170 degrees C and 315 degrees C. The sensitivity of both glow peaks to beta irradiation increases as the dopant concentration increases. The sensitivity is higher than that of LiF:Mg,Ti using the glow peaks 4+5 integral. Other properties like TL dose response, fading, sensitivity versus successive readout and ammealing cycles, sensitivity versus the heating rate, sensitivity to light and trapping parameter evaluation were also carried out.

Cerium↗

Thermoluminescent (TL) properties of the perovskite KMgF3 activated by Ce and Er impurities.

The perovskites are very interesting for their thermoluminescent properties and for their possible application as thermoluminescent dosimeters (TLD). In this paper we present results concerning the main dosimetric properties of KMgF3 activated by Ce and Er at various concentrations, i.e. annealing procedure, reproducibility of the TL signal, linearity and fading behaviour.

Journal Article↗

On the use of pediatric phantoms in the dose evaluation during computed tomography (CT) thorax examinations.

This paper presents the dosimetric results obtained during computed tomography (CT) thorax examinations, carried out using two different techniques, i.e., sequential CT (SQCT) and helical CT (HECT). The radiological examinations have been carried out on pediatric phantoms expressly designed and realized. Four different phantoms have been realized, according to the children shapes of 0, 2, 6, and 12 years old. The dosimetric measurements have been carried out using thermoluminescent dosimeters. The comparison of the dosimetric data obtained using the two different techniques shows that there is not any relevant difference between them as far as the entrance dose and the doses received by the critical organs are concerned.

Child↗

Dosimetric characterisation of a new production of MgB4O7:Dy,Na thermoluminescent material.

Thermoluminescent dosimetric characteristics of MgB4O7:Dy,Na are presented. MgB4O7:Dy,Na is a newly prepared TL material with attractive features for dosimetric applications, such as near-tissue equivalence, simple glow curve, high sensitivity and low fading. The dosimetric properties of this material examined in this study include glow curve shape, TL sensitivity, annealing procedure, photon dose response, minimum detectable dose, precision of TL measurements, reproducibility, energy response and fading characteristics.

Borates↗

A precise investigation on the TL behavior of LiF: Mg, Cu, P (GR-200A).

LiF: Mg, Cu, P is a TL material presenting unique dosimetric features. The TL sensitivity of this material was studied as a function of the annealing temperature and of the repeated cycles of annealing-irradiation-readout. A fading study was carried out over a period of 40 days with the purpose of checking the stability of the stored dosimetric information as a function of different annealing temperatures. A detailed statistical analysis of sets of data, obtained from repeated measurements on a group of ten dosimeters, is presented.

Fluorides↗

[The hadron therapy project].

The neologism "hadrontherapy" means radiotherapy with hadrons, which are the particles constituted by quarks, such as protons, neutrons and ions. The theoretical considerations about the clinical advantages this treatment modality can yield and the results obtained at the centers where it has already been used justify the proposal to project a center of this kind also in our Country. To this purpose, two of the authors of this paper (U. Amaldi, G. Tosi) founded the TERA Group formed by physicists, engineers and radiotherapists who work in close collaboration on a feasibility study for a hadrontherapy facility. The first aim of the Hadrontherapy Project is to design a center equipped with a synchrotron which, at the beginning, will accelerate negative hydrogen ions (H-) which will first produce 70-250 MeV proton beams and, then accelerate light ions (up to 16O) to 430 MeV/amu. This accelerator will serve four or five treatment rooms where patients can be irradiated simultaneously. Two rooms will be equipped with a fixed horizontal beam for the treatment of eye, head and neck tumors; the others will be equipped with rotating gantries to administer, in any clinical situation, really adequate treatment. Such a unit, when enough experience is fained, will allow at least 1000 patients to be treated yearly. The synchrotron injector will be designed so as to allow, parallel to the radiotherapy activities, other applications of medical and biological interest such as: the production of radioisotopes for diagnostic use (especially positron emitters), the analysis of trace elements through the PIXE technique and the production of thermal and epithermal neutrons for boron neutron capture therapy.

Biophysical Phenomena↗

A method for determining simultaneously the dose and the elapsed time since irradiation using TLDs.

Information about the time that has elapsed since an external radiation exposure is useful in order to determine the time of occurrence of an abnormal exposure in personal and accidental dosimetry is presented. This information can be obtained from certain irradiated thermoluminescent dosimeters. A computational method based on decay rates of thermoluminescence glow peaks has been used to estimate a range of suitable values of trap lifetimes of low temperature glow peaks. This provides a basis for the selection of an appropriate thermoluminescent material to assess not only the absorbed dose from a radiation exposure, but also the elapsed time. Experimental studies have been used to obtain additional information on decay rates as a function of energy, temperature and absorbed dose.

Accidents↗