Measurement of the thickness of a uniform metal layer using alpha spectroscopy

The thickness of the unresponsive layer of silicon on a surface barrier detector was undetectable. Alpha particles passed through the layer at normal incidence and at 60◦ with respect to the plane of the detector. Electronic drift obscured the difference between the two measured energies. The minimum detectable thickness of silicon for the system is (70± 8) μg/cm, or (30± 3) μm. Future experiments using this technique will require precise and highly stable data acquisition systems.