Efficiency response of an aged PIPS detector used in high-resolution alpha-particle spectrometry

Highlights: • Efficiency response of an aged PIPS detector was conducted. • Theoretical data and Monte Carlo simulation methods were involved for comparison. • Decontamination work shows an insignificant increase in the counting efficiency. • Novel method to evaluate the dead layer thickness for PIPS detector was developed. • An increase of the higher voltages can improve the counting efficiency and dead layer thickness. The experimental characterization of an aged PIPS detector used in an alpha-particle spectrometry is performed using a standard mixed source of ²³⁸U, ²³⁴U, ²³⁹Pu, and ²⁴¹Am. The variations in the detector efficiency and resolution (FWHM) at the main energy lines of the ²³⁸U, ²³⁴U, ²³⁹Pu and ²⁴¹Am source were investigated at all possible source–detector distances under chamber air pressure of $\sim$ 1.33 Pa. Finding shows that on average, the counting efficiency data obtained from measurements are lower than those obtained by theoretical data and Monte Carlo simulation (SOLANG and AASI) methods. A combination of polymeric strippable coating and both traditional wiping and cleaning method for the detector decontamination works only show a significant reduction in the background activity. The counting efficiency improvement process by an increase of the higher voltages within the recommended range results in a good agreement in the counting efficiency comparison and a slight decrease of the detector dead layer thickness. Novel method to evaluate the dead layer thickness for PIPS detector via the variations in experimental energy loss with respect source to detector distance using alpha standard sources of ²⁴²Pu has been proposed. This method can help to predict a default dead layer thickness value which will be as close as it was originally, is less than 50 nm from the manufacturer.