How precisely can the energy of a marker peak in an RBS spectrum be determined?

Abstract

We studied, how precisely the position of a marker peak in an Rutherford backscattering (RBS) spectrum can be determined. For that purpose, we chose the following approach. Repeatedly, the primary energy of a proton beam was set to one of three selected energies (100, 350 and 700 keV), RBS spectra of a thin Pt marker (on carbon) were measured by a conventional PIPS detector, and the energy position of the marker peak was determined by a least squares fit. During the measurement, the electronic system was kept at a constant temperature within ±0.1°C in order to avoid any signal drift. From a statistical evaluation of the peak position and of the actual primary energy information on the precision of both, energy setting and RBS evaluation was obtained. A relative uncertainty of 4×10 −4 for the energy setting, and an uncertainty of ≈1% of the detector FWHM for the evaluation of the marker position are found.