Sources of Variability in Alpha Emissivity Measurements at LA and ULA Levels, a Multicenter Study

Alpha emissivity measurements are important in the semiconductor industry for assessing the suitability of materials for use in production processes. A recently published round-robin study that circulated the same samples to several alpha counting centers showed wide center-to-center variations in measured alpha emissivity. A separate analysis of these results hypothesized that much of the variation might arise from differences in sample-to-entrance window separations.
XIA recently introduced an ultra low background counter, the UltraLo-1800 (“UltraLo”), that operates in a fundamentally different manner from the proportional counters used at most of the centers in the original study. In particular, by placing the sample within the counting volume, it eliminates the sample-to-entrance window separation issue noted above, and so offers an opportunity to test this hypothesis. In this work we briefly review how the UltraLo operates and describe a new round-robin study conducted entirely on UltraLo instruments using a set of standard samples that included two samples used in the original study.
This study shows that, for LA (“Low Alpha” between 2 and 50 α/khr-cm2) sample measurements, the only remaining site-to-site variations were due to counting statistics. Variations in ULA (“Ultra-Low Alpha” <2 α/khr-cm2) sample measurements were reduced three-fold, compared to the earlier study, with the measurements suggesting that residual activity variations now primarily arise from site-to-site differences in the cosmogenic background.
Related Articles
Network Time Synchronization of the Readout Electronics for a New Radioactive Gas Detection System
In systems with multiple radiation detectors, time synchronization of the data collected from different detectors is essential to reconstruct multidetector events such as scattering and coincidences. In cases where the number of detectors exceeds the readout channels...
Electronics Upgrades to the Green Is Clean Phoswich Detector Systems and Programmatic Implementation at LANL – Phase II Completion – 18403
Los Alamos National Laboratory (LANL) radiological facilities produce low-density room trash that, in many cases, is not contaminated with radioactivity. It has been estimated that 50 to 90% of low-density room trash is free of radioactive contamination and eligible...
New Algorithms for Improved Digital Pulse Arrival Timing With Sub-GSps ADCs
The ability to measure pulse times of arrival with resolutions at or below 100 ps is becoming increasingly desirable in various fields, typically for signals originating from photon detectors such as photomultiplier tubes (PMTs) or silicon photo-multipliers. Achieving...