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

Abstract

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 the radiopurity of the selenium double β-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 the validation of the BiPo-3 measurement with a calibrated aluminium foil is discussed. Results of the 208 Tl and 214 Bi activity measurements of the first enriched 82 Se foils of the double β-decay SuperNEMO experiment are reported. The sensitivity of the BiPo-3 detector for the measurement of the SuperNEMO 82 Se foils is A( 208 Tl) < 2 µBq/kg (90% C.L.) and A( 214 Bi) < 140 µBq/kg (90% C.L.

Background model of the CUPID-0 experiment

“…Ge-LD radiopurity is certified by UMICORE company. The contaminations of VIKUITI TM foils have been measured via Inductively Coupled Plasma Mass Spectrometry (ICPMS) at LNGS [9] and with a BiPo detector [12] (private communication). The limits of the other components are taken from Ref.…”

Status of SuperNEMO demonstrator

“…A successful R&D has been conducted in 2006-2010 with two prototypes that have demonstrated the proof of principle of such a detector to reach very low backgrounds [3]. A bigger detector called BiPo-3 has been designed and built in 2012 in order to measure the final 82 Se foils for the SuperNEMO Demonstrator with a total sensitive area of 3.6 m 2 [4]. It is divided in two modules, each of them hosting 20 pairs of optical sub-modules, composed of thin polystyrene scintillators coupled to 5" low background PMTs.…”

Development of an alpha-particle imaging detector based on a low radioactivity micro-time-projection chamber

“…For this experiment background is dominated by the 208 Tl and 214 Bi contamination present in the double beta emitter source foils. The SuperNEMO group has developed the BiPo-3 detector to measure the radioactive impurities in these foils with a sensitivity less than 2 µBq/kg (90%CL) for 208 Tl and 140 µBq/kg (90%CL) for 214 Bi [12]. Therefore, the background of 0νββ decay is not only a contamination by the end point of continuous energy in an ordinary 2νββ decay process, but also the radiative impurities such as 238 U and 232 Th in the detector.…”