Quantitative measurement of oxygen content in Si targets

Enriched self-supporting targets of 28,29,30Si are often used in the field of high resolution nuclear physics experiments. The Si targets were prepared by the thermal evaporation deposition or reduction–deposition methods. The targets, however, are always contaminated by oxygen as Si-material is easily oxidised. These contaminated targets lead to poor data with low S/N ratio. Thus it is very useful if one can estimate the amount of oxygen in the target quantitatively before experiments. s work we have developed a method to estimate the amount of oxygen in the Si target. We used α-ray and β-ray thickness gauges, which have different sensitivity to oxygen atoms. Namely, the α-ray gauge is more sensitive to light elements such as oxygen compared to the β-ray gauge. Thus one can deduce the amount of oxygen by comparing the oxygen thickness measured by α-ray gauge with that of the β-ray gauge. cy of a few percents can be obtained for the oxygen content in Si targets with a thickness of 1 mg/cm2. The present method can also be applied to heavy elements such as Ta2O5.