U$c_x$ target developments for the ALTO and the SPIRAL 2 projects

Abstract : The ALTO project (Accélérateur Linéaire auprès du Tandem d'Orsay) will provide an electron beam available at IPN Orsay at the end of 2005. The maximum energy will be 50 MeV with a maximum average intensity of 10 $\mu$A. It will be used for photofission in U$C_x$ targets. With the same target as that already used on the PARRNE set up it will be possible using ALTO to induce up to $10^11$ fissions/s instead of $10^9$ previously obtained with the 26 MeV/1 $\mu$A deuteron beam. Several ion sources will be adapted on the set up: ISOLDE FEBIAD type, surface ionization, laser,.... Moreover the electron beam could be used for other applications. Calculation about fission, energy deposition and dose rate will be presented, as well as the target-ion source adaptation on the PARRNE facility. For the SPIRAL 2 project planned at GANIL for 2008, the fission of $^{238}$U in uranium carbide target will be induced by a neutron flow created by bombarding a carbon converter with a 40 MeV high intensity deuteron beam. The target has been designed to reach more than $10^13$ fissions/s with a good release time. Calculation and technical considerations used to optimize the target design are detailed. One of main difficulties for this target is to maintain it at high temperature (more than 2000 °C) during 3 months. A tantalum oven has been studied and a prototype is under test at IPN Orsay. Some R&D studies on a high density target are in progress in collaboration with PNPI Gatchina and INFN Legnaro.