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

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 ∼ 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.