B. Gómez-Tubío

Combining PIXE and XRF with gamma-ray transmission to get accurate analysis of archaeological bronzes

Abstract A method that combines PIXE and XRF measurements with gamma-ray transmission has been developed. This method allows the measurement of the bulk composition of corroded bronze samples, which cannot be done with PIXE or XRF alone because these are near-surface techniques. The method is applied to several archaeological bronzes of the Final Bronze Age and First Iron Age of the region around Sevilla, Spain.

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.

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.

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.

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.