Mass Spectrometric Assay of High Radiopurity Solid Polymer Materials for Parts in Radiation and Rare Event Physics Detectors

Journal Article · Fri Nov 01 04:00:00 EDT 2019 · Nuclear Instruments and Methods in Physics Research, A.

DOI:https://doi.org/10.1016/j.nima.2019.162443· OSTI ID:1615252

Arnquist, Isaac J. ^[1]; Hoppe, Eric W. ^[1]; Bliss, Mary ^[1]; Harouaka, Khadouja ^[1]; di Vacri, Maria Laura ^[1]; Grate, Jay W. ^[1]

---

1. BATTELLE (PACIFIC NW LAB)

Plastic dielectric materials are required in radiation and rare event physics detectors as structural parts, insulators, seals, light reflectors, and in connectors. In order to observe events of interest rather than counting the radioactivity of the detector itself, these materials must be of high radiopurity. Using a mass spectrometric method, a number of solid plastic materials and parts were analyzed for mass levels of contaminants 232Th and 238U, which were used as an assessment of radiopurity. Sample preparation began with dry ashing the solid subsamples in very low mass containers of ultra low background electroformed copper (ULB EF-Cu) foil that had been cut and folded into boats serving as crucibles. Final determinations were carried out by inductively coupled plasma mass spectrometry (ICP-MS) with liquid nebulization sample solution introduction. Sample sizes were in the 25 mg to 1.25 g mass, and analyses could be completed in less than two days. Detection limits to pg/g (i.e., parts per trillion) levels are obtained and converted to radioactivity units microBq/kg of material. Determinations on poly(methyl methacrylate) (PMMA) gave values for 238U below 10 microBq/kg, while values for poly(chlorotrifluoroethylene) (PCTFE) rod stock material or acid-leached machined PCTFE parts were at or below 50 microBq/kg in 238U. Results for solid Purad poly(vinylidene fluoride) (PVDF) material are also reported at ca. 5 mBq/kg of 238U, although PVDF Solef 1010 raw material in powder and pellet form has been previously reported as low as 25 microBq/kg, and 200 microBq/kg 238U, respectively. An initial analysis of a polyetherimide(PEI) material, sold as ULTEM, indicated promising radiopurity with a found value of 30 microBq/kg for 238U. A variety of solid dielectric polymer materials were found with radiopurities at less than a milliBq/kg 238U and 232Th.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1615252
• Report Number(s): PNNL-SA-144425
• Journal Information: Nuclear Instruments and Methods in Physics Research, A., Journal Name: Nuclear Instruments and Methods in Physics Research, A. Vol. 943
• Country of Publication: United States
• Language: English

Related Subjects

polymer
mass spectrometry
ultralow background