Open AccessA sensitive assay technique for 210Pb in water
Author(s) -
D. Chauhan,
O. Chkvorets
Publication year - 2020
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1342/1/012111
Subject(s) - scintillator , ultrapure water , radiochemistry , electromagnetic shielding , contamination , liquid scintillation counting , shields , seawater , chemistry , nuclear physics , nuclear chemistry , analytical chemistry (journal) , physics , environmental chemistry , environmental science , detector , geology , environmental engineering , ecology , quantum mechanics , optics , biology , oceanography
SNO+ is a multipurpose neutrino physics experiment, located 2 kilometers underground in the SNOLAB facility in Sudbury, Canada. It is the successor of the SNO experiment, replacing the heavy water in the Acrylic vessel (AV) with 780 tons of liquid scintillator, Linear Alkyl Benzene (LAB). The AV is surrounded by 7000 tons of ultrapure light water, which shields the detector from naturally occurring radioactivity in the surrounding rock, PMTs, and PSUP. To achieve the radiopurity requirements, the water should be very clean and levels of U and Th contamination in the shielding water must be carefully controlled. A water assay technique, based on the capture of Ra and Th radioisotopes using Hydrous Titanium Oxide (HTiO), was developed by the SNO experiment. Ra sensitivities equivalent to 232 Th: 4×10 −16 gTh/D 2 O and 238 U: 3×10 −16 gU/g D 2 O were achieved with this technique [1]. The HTiO technique will be used in SNO+ to monitor 238 U and 232 Th contamination levels in the shielding water and the performance of the water purification system. For the lower energy measurements of interest to SNO+, radon daughter radioisotopes, especially 210 Po and 210 Bi supported by 210 Pb, are also important. Since water will be used in the purification of both the liquid scintillator and tellurium that will be chemically loaded in SNO+ to search for neutrinoless double beta decay, a technique to assay for 210 Pb in water was desirable. The SNO+ collaboration has extended the HTiO assay technique to allow measurement of 210 Pb in the water. This technique is capable of measuring 0.4 +/- 0.13 mBq/m 3 of 210 Pb for a 10 to nn e assay. The method developed and results of initial 210 Pb measurements are presented.