Speaker
Description
The development of next-generation rare-event experiments requires increasingly sensitive and rapid radioassay techniques for the screening and monitoring of detector materials. In particular, long-lived low-energy emitters such as
$^{210}$Pb and $^{3}$H represent a critical background source for several low-background applications, while remaining challenging to measure with conventional techniques.
In this contribution, we present recent developments in low-background Liquid Scintillation Counting (LSC) techniques performed at the University of Milano-Bicocca using a Wallac Quantulus 1220 system. The main focus is a rapid assay method for $^{210}$Pb in archaeological lead, developed within the R$\&$D activities of the RES-NOVA experiment. By combining optimized chemical preparation, pulse shape analysis (PSA), and low-background counting, the technique enables the simultaneous observation of the $^{210}$Pb decay chain ($^{210}$Pb, $^{210}$Bi, and $^{210}$Po) with sensitivities reaching the sub-Bq/kg level on timescales compatible with material screening and purification monitoring. The effects of chemical and color quenching, detector linearity, ROI optimization, and $\alpha/\beta$ discrimination will be discussed.
Additionally, preliminary investigations on the extension of similar LSC methodologies to $^3$H measurements in PbWO$_4$ crystals exposed to a fast-neutron spectrum at the ISIS ChipIR facility will be presented.
These measurements are relevant for the characterization of neutron-induced and intrinsic backgrounds in cryogenic detectors based on archaeological lead compounds.
These results demonstrate the potential of compact low-background LSC systems as flexible and relatively accessible tools for fast radioassay applications in rare-event physics experiments.