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The advent of multi-PW laser facilities world-wide opens new opportunities for nuclear physics. With this perspective, we developed a high efficiency neutron counter taking into account the specifics of a high intensity laser environment. Using GEANT4 simulations and prototype testings, we report on the design of a modular neutron-counter based on boron-10 enriched scintillators and high-density polyethylene moderator. This detector has been calibrated using a plutonium-beryllium neutron source and commissioned during an actual neutrons producing laser experiment at theLULI2000 facility (France). An overall efficiency of 4.37(59)% has been demonstrated during calibration with a recovery time of a few hundreds microseconds after laser-plasma interaction. We also tested using units of this detector in neutron time-of-flight configuration during the commissioning of the 1PW arm of the Apollon laser facility. Neutrons produced by the conversion of proton accelerated by the 1PW arm of the Apollon facility have been detected, of which we will present preliminary results.

Simultaneous particle-induced x-ray emission (PIXE) and particle-induced gamma-ray emission (PIGE) measurements in the 0-270 keV range with a low-energy hyperpure Ge detector have been performed on the outer surface and on an inner section of a dental composite filling extracted from a patient. The biomaterial has been identified as the fluorine-releasing Tetric Ceram dental composite. Compared to the native material, the dental filling evidenced changes occurring during the in vivo oral use. These included mainly CI and K accumulation and loss of Zr, Ba, Yb (by PIXE), and F (in the PIGE region). The changes were similar at the surface and inside of the dental filling for most of the above elements, indicating an unexpectedly high permeability of the material, maybe due to microscopic bulk fracture of the dental composite filling throughout its use. The PIGE spectra detected also AI and traces of Hf and Sm possibly associated with Zr and Yb. Changes in the ratio of the L lines of Yb and in the ratio of the 110- and 197-keV lines of F evidenced alterations in the matrix physical properties of the composite, associated with factors such as surface roughening by wear, grain size decrease by slow dissolution, and compositional variations. Further studies are needed to gain a deeper insight into the complex changes taking place in a dental composite filling.