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Electron anti-neutrinos produced by natural radioactivity inside the Earth - geoneutrinos - can be used as a unique direct probe in order to determine the amount of long-lived radioactive elements inside our planet and to constrain the radiogenic contribution to the terrestrial heat. The large volume liquid scintillator detectors, originally built to measure neutrinos or anti-neutrinos from other sources, are capable to detect them, as was demonstrated by KamLAND (Japan) in 2005 for the first time. Since then geoneutrinos were measured with high statistical significance both by the KamLAND (Japan) and by Borexino (Italy) underground experiments. Several future projects of large volume detectors have geoneutrinos among their scientific goals. The status-of-art and scientific potential of this new inter-disciplinary field was presented.

The determination of the proton rms charge radius with an accuracy of 10−3 is the main goal of our experiment, opening the way to check bound‐state QED predictions in hydrogen to a level of 10−7. The principle is to measure the 2S1/2(F = 1) − 2P3/2(F = 2) energy difference in muonic hydrogen (μ−p) by infrared laser spectroscopy to a precision of 30 ppm. Very low‐energy negative muons are stopped in 0.6 mbar of hydrogen gas, where, following the μ− atomic capture and cascade, 1% of the muonic hydrogen atoms form the metastable 2S state with a lifetime of 1.3 μs. A 6 μm laser pulse is used to drive the 2S → 2P transition. When on resonance, the laser induces the transition, and the subsequent muonic deexcitation to the 1S state emits a 1.9 keV x ray which is detected by avalanche photodiodes. The resonance frequency, and hence the Lamb shift and the proton charge radius, is determined by measuring the rate of laser‐induced x rays as a function of the laser wavelength. Some details of the experiment, recent measurements and improvements will be presented.

The goal of the DEAR (DAΦNE Exotic Atom Research) experiment is the precision measurement of the Kα line shift and width, due to the strong interaction, in kaonic hydrogen and the first similar measurement in kaonic deuterium. The final aim is a precision determination of the antikaon‐nucleon isospin dependent scattering lengths, in order to obtain the kaon nucleon sigma terms. In the first phase of the experiment, dedicated to the calibration and optimization of the setup, the experiment collected data on gaseous kaonic nitrogen: for the first time a pattern of three transitions (7 → 6 at 4.6 keV, 6 → 5 at 7.6 keV and 5 → 4 at 14 keV) was measured, and the corresponding yields obtained. The kaonic hydrogen measurement followed, in the last months of 2002, for a total integrated luminosity of about 60 pb−1 . Data analyses are in progress, preliminary results being hereby presented, together with those on kaonic nitrogen. Future measurements: kaonic deuterium, kaonic helium and precise determination of the charged kaon mass are planned in the framework of the SIDDHARTA (SIlicon Drift Detector for Hadronic Atoms Research by Timing Application) experiment, which will replace DEAR on DAΦNE.