Background reduction in 236U/238U measurements

In this study, we report preliminary results on the characterization of the presence of molecular interferences when using UO−, UC− and UC2− as injected molecular ions. In particular the possibility to stabilize the current yield from carbide cathodes has been investigated: it was found that the best cathode preparation procedure is obtained pressing U salts baked at 800 °C mixed with graphite and Al powder. Moreover, the 238U background in 236U measurements is strongly reduced injecting UC− ions, as verified using a time-of-flight detection system. On the other hand, 235U interference is larger with respect to UO− injection, but this increase is smaller than expected on the basis of abundances of 13C and 17O in UC and UC2 molecules on one side and UO, on the other.