**2.1 Ion beam analysis**

Ion Beam Analysis is founded on the basic physics of interactions between incident particles and target atoms (IBA) [7, 8]. IBA has been used extensively in the nuclear

sector using the four standard methodologies [9]. In the nuclear industry, IBA is usually used in determining the composition of nuclear fuels, undertaking radiation damage studies, characterization of nuclear waste, and investigating nuclear incidents and accidents [10]. Rutherford Backscattering Spectrometry (RBS), Elastic Recoil Detection Analysis (ERDA), Nuclear Reaction Analysis (NRA), and Proton-Induced X-ray Emission (PIXE) are the traditional techniques used. The RBS, NRA, and ERDA methods are categorized as nuclear methods, whereas the PIXE method is classified as atomic [7]. Particle-Induced Gamma Ray Emission (PIGE), Charged Particle Activation Analysis (CPAA), Scanning Transmission Ion Microscopy (STIM), Ionoluminescence, Secondary Ion Mass Spectroscopy (SIMS), and Ion Beam Induced Charge imaging (IBIC) are some of the novel methods available.

RBS is one of the nuclear techniques used extensively in the nuclear industry for the investigation of materials' near-surface layers. It takes its history from Sir Ernest Rutherford's scattering experiment in 1911 which led to the discovery of the atomic nucleus. The technique is primarily used to quantify the composition of a material and measure the elemental depth profiles [7]. The method's usual parameters are 1.5 to 14 μm H+ or He+ ions with energies ranging from 500 keV to 4 MeV. RBS records the elastic backscatter of the projectiles from the sample nuclei. Moreover, the measured energy is influenced by the mass of the target nucleus as well as the depth of the scattering event beneath the surface. It is non-destructive and very sensitive to heavy elements. Usually, an energy-sensitive detector—typically a solid-state detector—records the energy of the backscattered particles. The drawback of the technique is that it requires a combination of other techniques such as NRA and ERDA.

ERDA involves inducing elastic scattering in a material with ion beams. This leads to the determination of the yield and energy of particles ejected out of the surface region of samples under the bombardment [11]. Quantitative measurements from the experiment then help to determine the composition of the material. Elastic recoil detection analysis as was opined earlier normally comes in to complement the RBS. In RBS, the incident particles backscattered from target atoms are detected, whereas, in ERDA, the forward recoil target atoms are rather detected directly. The technique's application is mostly on depth profiling of multiple light elements.

Nuclear Reaction Analysis as the name suggests is where incident ion beams induce nuclear reactions (radioactivity) which are used to determine the elemental composition of materials. The technique works on the detection of radiation from the interaction of the projectile and nucleus. The NAR technique involves the study of the reactions of hydrogen at the surface and subsurface of materials. Nuclear activation analysis is also another type of NRA used by several facilities to determine the elemental composition of materials. NRA is a good method for measuring the concentration of certain elements (impurity or implanted ions) and their depth distribution in biological samples.

The PIXE technique involves the generation of x-rays as a result of bombarding the material under study with an ion beam [6]. This ion beam displaces electrons in the inner shell thereby forcing electrons in the outer shells to fill the space and in the process dissipates energies in the form of X-ray. The x-ray released characterizes the elemental composition of the material under study. This technique is also nondestructive, works faster, and is accurate.
