Thickness Measurement of Light Element Thin Target on Heavy Element Substrate with RBS Method

The accuracy of target thickness has a great influence on the reliability of the result in nuclear reaction experiment. In order to measure the thickness of light element thin target on the heavy element substrate, a 1.5 MeV proton beam was used to measure a thin ⁷⁴Ge target evaporated on a ¹⁸¹Ta substrate which has a thickness of 300 μm with Rutherford backscattering (RBS) method. The difference of measurement result between RBS method and weighing method is small, but the signal-noise-ratio increases from 1∶2 000 to 1∶12 and the thickness relative uncertainty decreases from 10% to about 5% compared with weighing method. SIMNRA simulation was also performed to check the measurement result, which matches well with experiment energy spectrum. RBS method can effectively improve the signal-noise-ratio and uncertainty when measuring the thickness of light element thin target on a heavy element substrate, especially when the substrate is much heavier than the target, which provides a good basis for the data analysis in nuclear reaction experiment.