Physics & Applications of the new TOF-ERD System Installed at Surrey Ion Beam Centre

The Surrey Ion Beam Centre (SIBC) has a new Time of Flight – Elastic Recoil Detection (TOF-ERD) system allowing for measurements using an alternative technique for ion beam analysis (IBA). IBA is a useful tool in determining the composition of samples such as semiconductors; materials having variable conductivities being crucial for electronics, or for polymers, the basis of plastics. Certain interactions occur when ions enter a sample. Ions can backscatter off atoms for the technique Rutherford Backscattering Spectrometry (RBS). RBS causes low damage to samples and for simple samples, generates a spectrum allowing easy determination of elements present. However, it is impossible to detect lighter atoms like Hydrogen. Alternatively, an ion can knock atoms out from the sample in an alternate technique: “Elastic Recoil Detection” (ERD). ERD is able to measure lighter elements such as H. A drawback however, is being unable to account for build-up of loss of material which damages the sample. TOF-ERD, similar to ERD, has atoms knocked out of the sample which then pass through two gates giving the Time of Flight (TOF) measurement before entering a detector [1]. TOF-ERD uses heavier beam species such as Cl and I allowing measurement of both light elements, like hydrogen, and heavier elements. However, this technique still causes damage. The software Potku, first released in 2014 with ongoing development, is used to analyse and present the measurements [2]. High intensity regions appear that relate to atoms of different masses. By identifying these elements Potku generates a depth profile showing the variation of elemental concentrations. This poster will outline the physics and apparatus of TOF-ERD along with analysis of hydrogenated and deuterated polystyrene. References [1] J. Julin et al, Rev. Sci. Instrum. 87, 083309 (2016) [2] K. Arstila et al., Nucl. Instr. and Meth. in Phys. Res. B 331 (2014) [2] K. Arstila et al., Nucl. Instr. and Meth. in Phys. Res. B 331 (2014