Abstract:
Alpha particle emission – even at extremely low levels – is a significant issue in the search for rare- events (i.e., double beta decay, dark matter detection) and in other industrial applications such as semiconductor packaging. Traditional emissivity measurement techniques require long counting times to measure the sample rate above the instrument’s intrinsic background, which is typically much larger in magnitude. A new commercially available instrument developed by XIA uses pulse shape analysis to discriminate alpha emissions produced by the sample from those produced by the instrument itself. Recent experience with this system has uncovered two additional sources of background: cosmogenics and radon emanation from internal components. We will review the theory of operation and pulse shape analysis techniques used in XIA’s alpha counter. We will then explore data suggesting the origin of the additional sources of background. Finally, we will discuss proposed enhancements to the system to extend the pulse shape analysis technique further, so that these additional sources of background can also be identified and rejected.
