The BiPo-3 detector for the measurement of ultra low natural radioactivities of thin materials

Understand

The BiPo-3 detector, running in the Canfranc Underground Laboratory (Laboratorio Subterr\'aneo de Canfranc, LSC, Spain) since 2013, is a low-radioactivity detector dedicated to measuring ultra low natural radionuclide contaminations of $^{208}$Tl ($^{232}$Th chain) and $^{214}$Bi ($^{238}$U chain) in thin materials.

• The total sensitive surface area of the detector is 3.6 m$^2$.
• The detector has been developed to measure radiopurity of the selenium double $\beta$-decay source foils of the SuperNEMO experiment.
• In this paper the design and performance of the detector, and results of the background measurements in $^{208}$Tl and $^{214}$Bi, are presented, and validation of the BiPo-3 measurement with a calibrated aluminium foil is discussed.