Evaluation of energy loss from DUAL-TOF spectra

Abstract

The energy loss of slow ions can be measured with high precision using our two-branched time-of-flight set-up (DUAL-TOF): one branch (reference line) yields the momentary beam energy with a relative accuracy ΔE E < 1 × 10 −3 . while from the other branch (target line) the TOF-delay due to the energy loss of the ion beam in a thin target foil is obtained. The start and stop signals are derived from an electrostatic beam chopper and from stop detectors (micro-channel plates), respectively. The time-correlated data from both branches are stored in a two-dimensional (2-D) multichannel-analyzer by a coincidence technique. Evaluating the 2-D spectrum we are able to get rid of the energy fluctuations of the ion beam, thereby gaining precision. In this contribution we present first results of DUAL-TOF energy-loss measurements. Thin Mg-layers have been evaporated in situ onto thin C-foils. The target thickness has been determined by RBS. In order to show illustrating examples, energy loss data for 65 keV protons and for 120 keV deuterons are shown as measured by our DUAL-TOF.