THE ORIGIN OF SAMPLE MEMORY IN THE CHALK-RIVER ACCELERATOR MASS-SPECTROMETRY SPUTTER ION-SOURCE

The origin of memory effects in the Chalk River accelerator mass spect rometry sputter ion source has been studied by tracer and elastic-reco il-detection surface analysis techniques. For Cl-36 measurements, the results indicate that the memory arises from contamination of the regi on immediately surrounding the sample and that it can be mitigated by operating this portion of the ion source above 350 degrees C. This has reduced memory effects by a factor of 10 or more and has resulted in a similar improvement in background. (C) 1996 American Institute of Ph ysics.