Time-resolved investigations on any phase of matter through pump-probe methods involving FELs and laser beams is a new frontier for modern science. The underlying problem for these experiments is the requirement of an accurate spatial and temporal superposition of pump and probe beams on the sample: at the present, this is still a critical procedure, also in term of large time needed going to the detriment of the available beamtime. A more efficient approach for quickly achieve the superposition and synchronization of the beams, an integrated device based on a novel technique based on an integrated device allowing the simultaneous characterization and the fast spatial and temporal overlapping of the beams, reducing the alignment procedure from hours to minutes. The system has been designed and developed in collaboration with FEL group of Elettra Synchrotron in Trieste and Molecular Foundry in Berkeley, US.  It consists of an array of micro-wells produced on fused silica substrate filled with suitable phosphors powder to produce a pixelated phosphorus detector (PPD) previously proposed by our group [A. Matruglio, S. Dal Zilio, R. Sergo, R. Mincigrucci, C. Svetina, E. Prin-cipi, N. Mahne, L. Raimondi, A. Turchet, C. Masciovecchio, M. Lazzarino, G. Cautero, and M. Zangrando, Journal of Synchrotron Radiation 23, 29 (2016) ] and Al2O3 embedded zones with precise size and geometry.

This would permit to employ adjacent portions of the same surface to spatially and temporally superpose the FEL and laser beams. A simple strategy to drastically increase the SNR is to operate in transmission (thus looking for a change in trasmittivity induced by the FEL pulse) and to create a pinhole around the Al2O3 zones. The pinhole, realized by a reflective material for the visible-IR  laser, should be smaller or comparable with the size of the FEL beam. This permits of cutting the circular crown of the laser spot that would not interact with an the FEL excited portion of the Al2O3, with the FEL excited portion of the Al₂O₃.

We demonstrated that the PPD2.0 increases the contrast by a factor 7 with respect to the bulk Al₂O₃ crystal, being contemporarily exploitable for the spatial overlapping procedure. This allows to be more efficient in the overall superposition procedure in terms of time and spatial precision since the use of different crystals with different characteristics is not required.