I. Ortega-Feliu

X-ray and gamma-ray based spectroscopic analysis of a millefiori Roman glass fragment: degradation of sunken glass from a shipwreck

Particle induced X-ray and gamma-ray techniques (PIXE and PIGE) carried out on an external beam line, combined with X-ray dose monitoring and a helium atmosphere, have been performed in this work. These atomic and nuclear techniques, simultaneously used for complementary chemical information, have been demonstrated to be of great value as they provide non-destructive compositional information avoiding the use of vacuum chambers or sample preparation. The analytical set-up implemented has been applied in an archaeometry study: a millefiori glass fragment recovered from the sea in 1976 from a merchant Roman shipwreck (1st century B.C.). The fragment is composed of a yellow and blue millefiori base structure decorated with large coloured pieces and presents high levels of degradation due to the aquatic medium in which it has stayed for several centuries. The interest of the study lies in that the degree of deterioration is higher in the millefiori structure than in the coloured pieces. The composition of both has been determined in a non-destructive way in order to study the manufacturing process, the nature of the coloured pieces and the reason for the different degradation processes. According to the results, the coloured pieces are glass fragments similar in composition to the millefiori structure, which is a natron-based sodium silica glass, similar to other analysed Roman glasses. The blue colour is due to cobalt and copper elements. The use of one source of silica, probably coastal sand characterised by high contents of sulfur and phosphorus, can be inferred from the results.

Performance of ultrafast laser written active waveguides by rigorous modeling of optical gain measurements

An Er:Yb co-doped P2O5-La2O5 based glass has been synthesized and used for producing 1.6 cm-long active optical waveguides using a low repetition (1 kHz) rate Ti:Al2O3 fs-laser amplifier. Before processing, the laser energy deposition profile for an elliptically shaped beam was simulated, and the best processing conditions for optimizing the focal volume shape, minimizing non-linear propagation effects, were determined. Under these conditions, a multi-scan writing approach was used to maximize the refractive index change induced and to minimize the transmission losses. After processing, the optical powers propagating inside the waveguide (pump absorption, co- and counter-propagating ASE, low signal gain, …) were measured for uni- and bi-directional pumping schemes, and the measurements were simulated and fitted using an ad hoc developed model to describe the behavior of laser written waveguides. The measurements provide internal gain figures comparable to the best ones reported in phosphate glasses for low repetition rate writing even with larger insertion losses. The simulations provide access to key parameters of the waveguide characteristics (coupling losses and propagation losses, Yb3+ ⇔ Er3+ energy transfer rates, Er3+ upconversion coefficient), which have been used to model the expected performance of these structures in terms of length and doping level. A moderate increase of the Er3+ and Yb3+ doping level would potentially lead to net gain values up to 9.4 dB for a waveguide length of 25 mm.

Compositional and micro-structural study of joining methods in archaeological gold objects

Trabajo presentado al EXRS2016 - European Conference on X-ray Spectrometry, celebrada en Gothenburg (Suecia) del 19 al 24 de junio de 2016.

Compositional and microstructural study of joining methods in archaeological gold objects: Study of joining methods in archaeological gold objects

Trabajo presentado al EXRS2016 - European Conference on X-ray Spectrometry, celebrada en Gothenburg (Suecia) del 19 al 24 de junio de 2016.

Standardless semi-quantitative analysis by PIXE

A method based on the refinement of atomic and experimental parameters developed for the description of PIXE spectra is presented and applied to standardless semi-quantitative PIXE analysis. This method was implemented in the sofware PAMPA (Parameter Assessment Method for PIXE Analysis) and consists in minimizing the quadratic differences between an experimental spectrum and an analytical function proposed to describe it. The first results of PAMPA are presented for the quantification of synthetic and mineral, thin and bulk samples, and they are compared with the results obtained with a commercial software.

Análisis PIXE en muestras óseas subfósiles: Ensayo de un protocolo de preparación

Los huesos subfosiles son una fuente de informacion que va mas alla del estudio taxonomico y tafonomico a nivel macroscopico. En este sentido, las tecnicas de ADN antiguo y las fisico-quimicas estan aportando nuevas perspectivas a los analisis paleobiologicos llegando a describir patrones de domesticacion, migracion, contaminacion ambiental, etc. No obstante, el proceso de diagenesis, por el que pasan todos los restos subfosiles, conlleva una problematica asociada que afecta a este tipo de estudios geneticos y fisico-quimicos. Ademas de las perdidas de material que se producen por erosion, la composicion quimica se puede ver afectada por procesos de disolucion, precipitacion, absorcion, sustitucion mineral y recristalizacion. Todos estos problemas de contaminacion estan siendo tratados por diferentes especialistas que preparan las muestras en funcion de los objetivos a alcanzar y de las tecnicas a utilizar. Con este trabajo de investigacion se pretende desarrollar un protocolo de preparacion de muestras efectivo para la deteccion de contaminaciones ambientales prehistoricas e historicas a partir del estudio de elementos traza con una tecnica no destructiva, PIXE.

High gain, short length optical amplifier in heavily doped phosphate glass for miniature optics

In this work we demonstrate the production of a high gain, short length waveguide amplifiers and lasers produced by state of the art femtosecond (fs) laser micromachining.

Nuevo sistema portátil de micro-fluorescencia de rayos X basado en óptica de policapilares para aplicaciones en Patrimonio Cultural

Trabajo presentado al I Congreso Internacional “El Patrimonio Cultural y Natural como motor de desarrollo: Investigacion e Innovacion” celebrado en Jaen del 26 al 28 de enero del 2011.