Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Direct method for the quantitative analysis of surface contamination on
  ultra-low background materials from exposure to dust   In this work we present a method for the direct determination of contaminant
fallout rates on material surfaces from exposure to dust. Naturally occurring
radionuclides K-40, Th-232, U-238 and stable Pb were investigated. Until now,
background contributions from dust particulate have largely been estimated from
fallout models and assumed dust composition. Our method utilizes a variety of
low background collection media for exposure in locations of interest, followed
by surface leaching and leachate analysis using inductively coupled plasma mass
spectrometry (ICP-MS). The method was validated and applied in selected
locations at Pacific Northwest National Laboratory (PNNL) and the SNOLAB
underground facility.

5
The categories of this paper are: gr-qc
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg