Feasibility evaluation of the application of Silicon Drift Detectors to PIXE detection of medium-light elements

We have developed a detection module based on a Silicon Drift Detector to assess the feasibility of medium light elements (down to Z=11 - Na) detection in PIXE measurements at on of the beam-lines with external proton beam at the Tandetron in LABEC (INFN, Firenze, Italy). The achieved energy resolution is of the order of 134 eV FWHM at Mn - Kalpha line for count rates of about 100 Hz with the detector cooled at -30degC. The requirement of medium-light elements detection together with the low beam current limit imposed by the analysis of cultural heritage objects impose to shorten as much as possible the sample-detector distance thus increasing the rate of back scattered protons. In order to limit the rate of back-scattered protons we have coupled a polycapillary lens to the detector. In this paper we will discuss the detection module characteristics and concentrate on the measurements carried out at LABEC to assess the detection module performance in true experimental conditions.