Study of236U/238U ratio at CIRCE using a 16-strip silicon detector with a TOF system

Abstract

Accelerator Mass Spectrometry (AMS) is presently the most sensitive technique for the measurement of long-lived actinides, e.g. 236 U and x Pu isotopes. A new actinide AMS system, based on a 3-MV pelletron tandem accelerator, is operated at the Center for Isotopic Research on Cultural and Environmental Heritage (CIRCE) in Caserta, Italy. In this paper we report on the procedure adopted to increase the 236 U abundance sensitivity as low as possible. The energy and position determinations of the 236 U ions, using a 16-strip silicon detector have been obtained. A 236 U/ 238 U isotopic ratio background level of about 2.9×10 −11 was obtained, summing over all the strips, using a Time of Flight-Energy (TOF-E) system with a 16-strip silicon detector (4.9×10 −12 just with one strip).