Current status and future direction of MALT, The University of Tokyo.

MALT (Micro-Analysis Laboratory, Tandem accelerator) at The University of Tokyo is a research and service facility for elemental and isotopic analysis using a tandem accelerator for AMS, PIXE and NRA. Among these, AMS is the most promising technique at MALT. After the AMS-8 conference in 1999, the overall performance was greatly improved for 10Be-, 26Al- and 14C-AMS. For 10Be-AMS, the negative ion current was considerably increased by a new Cs-ionizer system and the replacement of the compound powder (Nb instead of Ag) for the BeO target. More than 3 μA current of BeO− ions can be extracted while it had been typically 1 μA before. For 26Al-AMS, by examining the sample ignition process, the negative ion gain was increased more than 200 nA (typically 100 nA before), which greatly improved the overall efficiency. For 14C-AMS, the 12C− current dependency problem has been moderated substantially by installing a fine controllable Cs oven and careful beam tuning. As a consequence, the precision is now better than 0.5% for modern carbon. In addition, systems for 36Cl-AMS and 129I-AMS are currently being developed for future research programs at MALT. [Copyright &y& Elsevier]