The performance of the Ljubljana ion microprobe

In August 2000 the setup of the Ljubljana ion microprobe, based on OM 150 triplet, has been completed. The beam line is installed at the 10degrees exit port of the 2 MeV Tandetron accelerator. It is equipped with motor driven slits, a precise five-axis goniometer and a spherically shaped measuring chamber with detectors for PIXE, PIGE, PESA, SE and RBS. In order to understand the beam optics along the complete system, consisting of the tandem accelerator and the beam line optical elements, an interactive computer code, based on a linear approximation, has been developed. The program is used both to determine the optimal parameters of the tandem focusing system in its daily use and to develop new beam line configurations. Test measurements performed on a copper grid yielded a spatial resolution of 1.0 x 1.5 mum(2) in the high current mode (30-100 pA) and 0.5 x 0.9 mum(2) in low current mode (10(4) counts/s). First analytical results confirmed excellent performance of the new Ljubljana ion microprobe. (C) 2002 Published by Elsevier Science B.V.