# FUXYA2020: A Low-Cost Homemade Portable EDXRF Spectrometer for Cultural Heritage Applications
## 1 Introduction  
Energy dispersive X-ray fluorescence (EDXRF) is a very suitable analysis method for the examination of cultural heritage materials and is widely used, thanks to its relative straightforwardness of use and its totally non-destructive character, allowing for analysis without any sample preparation. EDXRF has numerous applications in this field, as it is able to detect elements from sodium to uranium, and in certain cases can go down to carbon [1], moreover the data treatment (e.g., qualitative analysis, PCA [2; 3], semi-quantitative analysis) [4; 5; 6], quantitative analysis) makes this technique suitable to answer numerous questions. Thus, EDXRF is commonly used to perform provenance studies on ceramics, coins and glass [3; 7; 8; 9], to evaluate corrosion processes on metals [10; 11], find restorations in paintings [12; 13; 14] or fake objects [15], or to identify worn out pigmentation in ancient polychromies [16; 17; 18; 19]. These are just few examples of potential applications. Anyway, we also must consider that XRF investigates deep into the artifacts (depending on the energy of the fluorescence radiation and the composition of the sample, the volume investigated can be a few tens of micrometers for light matrices to less than one micrometer for metals). The technique is then not always suitable when the aim is to distinguish the composition of the different layers composing the sample, and it is only a comprehensive elemental composition that is obtained. The only way to distinguish thelayers is to get a priori knowledge of the composition of the sample, or to analyze the bulk if feasible. Nevertheless, new set-ups are now also being developed to analyze layered samples [20; 21; 22]: for example, performing an angular scanning [23; 24; 25], evaluating the ratio of the fluorescence lines [26; 27], exploiting MA-XRF mapping [28; 29; 30], or through Monte Carlo simulations [11; 31; 32]. In the last twenty years, several portable and handheld EDXRF spectrometers have become commercially available, each with its own distinguishing features and fields of application. Their diversity of designs and their features affect the final price of this kind of instrumentation, making it accessible to a small circle of researchers. It must be pointed out that some hand-held instruments do not offer the easy possibility of working on raw spectra, but only to gain a quantitative evaluation of element concentrations [2; 33]. This aspect makes these instrumentations fake user-friendly, as they require high skills to handle and customize the routines and analytical modes provided by the manufacturer. Moreover, not all the materials pertaining to the cultural heritage field can be described in terms of element concentration, as, for instance, is the case of pigments [34], where dilution, binder and layer thickness highly affect the possibility (and the meaningfulness) of having a quantitative evaluation. The same applies to the study of any layered sample, such as lustered or glazed ceramics [35], or to ink decorations [16]. From these starting considerations, in the last decade some research groups have developed their own homemade spectrometers; some of them clearly demonstrated that basic spectrometers can be useful for the characterization of CH materials held in the Museums [36]. In 2010, a research group from the Physics Institute of the UNAM, Mexico, developed SANDRA (sistema de analisis no destructivo por rayos X or system for non-destructive analysis using X-rays) especially for the study of Mexican Cultural Heritage collections [37]. This system is equipped with changeable tubes (namely, 75 W Mo, Rh and W X-ray tubes) and detectors (Amptek Si-PIN and Cd-Te detector) that are selected and combined depending on the elemental range of interest. One year later, LABEC laboratory of Istituto Nazionale di Fisica Nucleare (INFN), in collaboration with ICVBC of Consiglio Nazionale delle Ricerche (CNR), developed a custom-realized portable XRF spectrometer [38].