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Collisional production of fast metastable hydrogen atoms from cold H2: toward twin atoms

We have investigated the production of fast metastable H(22S) coming from the dissociation of cold H2 molecules produced in a Campargue nozzle beam after crossing with an electron beam emerging from a high intensity pulsed electron gun. We have achieved dissociation by electron impact in order to avoid limitations due to the selection rules governing radiative transitions. Two detectors, placed 230 and 254 mm away from the collision centre, have analysed the neutral fragments as a function of their time-of-flight through localized quenching of H(22S) in H(22P) and Lyman-α detection. Performing coincidence experiments in order to ascertain the existence of the H(22S)–H(22S) dissociation channel is appealing due to the anlysis of the spectra.