Studies of uranium carbide targets of a high density

International audience; Production of Rb, Cs and Fr isotopes from uranium carbide targets of a high density has been investigated. The UC target material with a density of 12 g/cm3 was prepared in a form of pellets of 2 mm thickness, 11 mm in diameter and grain dimensions of about 20 microns. Two targets were tested on-line at the same temperature conditions: a) a reference small target with a thickness of 4.5 g/cm2; b) a big massive target with a thickness of 91 g/cm2. The yields and release efficiencies of the nuclides with the half-lives from some minutes to some milliseconds produced from the investigated targets have been presented. A preliminary analysis of the obtained results has shown an increase of the produced nuclide yields proportionally to the target thickness even for very short-lived isotopes 214Fr (T1/2=5 ms) and 219Fr (T1/2=20 ms). One month off-line heating test of a big target at a temperature of 2000 °C has been conducted. The yields and release of Rb, Cs and Fr measured on-line before and after the heating test coincided in the limits of measurement errors that demonstrated the conservation of the developed target unit parameters. The construction of a big target with the mass about 0.7 kg prepared presently at IRIS has been discussed.