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The production of neutral pions in nucleus nucleus collisions with ztzt MeV/u Ar projectiles from the accelerator" GANIL has been observed. The angular distributions indicate a collective production process, and the pion spectre reflect properties of the collision dynamics.In proton-proton collisions neutral pions can be produced only above the threshold energy of 280 MeV in the laboratory. In collisions of nuclei a pion production is possible at smaller specific energies either as a consequence of the extra momentum of at least one of the nucleons clue to its intranuclear Fermi motion 1 or alternatively through the cooperative action of several nucleons in the collision, i.e. a collective effect. Previous pion production data ~'3 from subthreshold nucleus-nucleus collisions ranging from 183 down to 85 MeV/u were explained by Fermi motion enhanced N-N-collisions. Subsequently it was demonstrated" that at energies as low as 85 MeV/u and below N-N-contributions to the pion production should be rather small and that they depend strongly on the far tails of the Fermi distribution and on the details of the extrapolation into the region off the energy shell.Additionally the Pauli principle blocks the creation of a pion when the two colliding nucleons do not have enough momentum left to find an empty cell in phase space; this effect was shown 1 to cut off any pion creation below about 50 MeV/u. Pion production at even lower energies thus would strongly indicate the existence of collective effects in the collision dynamics. Pion spectra and angular distributions should thus contain information about the details of the collision dynamics and especially they should help to answer the question, how the energy of the relative motion is converted into internal energy, which eventually is high enough to lead to pion production.The experiments were performed at the "~ beam of the two coupled isochronous cyclotrons (GANIL) at Caen, which came into operation recently, We used a beam of 44 MeV/u at an average intensity of 109 particles/s. The integrated dose, as measured in a Faraday cup with an accuracy of 10%, was about G ~ 1013 projectiles on each of the three targets Ca, Sn and U, which had a thickness of 30 mg/cm 2, determined by weighing to within 5%. The very low pion production rates required a high detection efficiency; we obtained more than 1% for neutral pions by observing the two decay

The SPIRAL1 (Système de Production d'Ions Radioactifs Accélérés en Ligne) facility at GANIL (Grand Accélérateur National d'Ions Lourds) is developing new techniques to access nuclei in the neutrondeficient isotope region far from the stability-valley, with Z ranging from 30 to 60. The availability of different primary beams, ranging from carbon to uranium with energies up to 95 MeV/A, gives an opportunity to produce a large variety of radioactive ion beams. The production of neutron-deficient short-lived alkalis by fusion-evaporation reactions is the focus of this work. A simple and compact target ion source system is designed to produce isotopes of 74 Rb (= 64.8 ms) and 114 Cs (= 570 ms). The efficiencies of the different processes involved in the production are evaluated. Radioactive recoils are produced by the interaction of heavy-ion beams, respectively 20 Ne@10 13 pps and 58 Ni@10 12 pps, with a thin 58 Ni target. High atom-to-ion transformation (ATI) efficiency should be obtained above 70% and 90% for 74 Rb and 114 Cs nuclei respectively. The expected intensities of the RIBs are estimated to be about 10 4 pps at the exit of the TISS.

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