Hamburg 2009 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 5: AMS-Developments

MS 5.8: Vortrag

Dienstag, 3. März 2009, 15:45–16:00, VMP 8 R05

Energy loss and straggling measurements for AMS — •Christof Vockenhuber, Vasily Alfimov, Arnold Müller, Martin Suter, and Hans-Arno Synal — ETH Zurich, Zurich, Switzerland

Energy loss in matter is important for particle identification in Accelerator Mass Spectrometry (AMS). Isobaric contamination can be identified by their different specific energy loss as it is usually done with ionization chambers at energies above 1 MeV/u, but other methods (e.g. passive absorption) are also used. At lower energies the energy-loss straggling increases relative to the difference in energy loss, thus becoming the limiting factor for particle identification.

While energy loss in matter is relatively well understood and predictions can be made with often sufficient precision, energy-loss straggling is more difficult to predict. In addition, measurements of energy-loss straggling in foils are often hampered by inhomogeneities leading to additional broadening of the energy distribution. At energies relevant for the small AMS systems TANDY and MICADAS energy loss and energy-loss straggling of heavy ions in highly homogeneous silicon nitride foils were measured previously [1].

We are extending these measurements to other materials and energies at and below the stopping power maximum. An improved data set should eventually lead to a better understanding of the physical processes and to improved predictions of energy-loss straggling.

[1] G. Sun et al., Nucl. Instr. Meth. B 256 (2007) 586