Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: TEM observations on palladium samples aged up to 8 years under tritium   Transmission electron microscopy (TEM) experiments were carried out on aged
under tritium palladium powder samples. The experiments were devoted to the
study of the evolution of 3He bubbles (size, density) appearing during aging.
The study, using a new sample preparation, was focused for the first time on
long aging time, up to 8 years. The TEM results indicated the presence of
nanometer size bubbles (2 - 3 nm in diameter) with densities close to 5x10^23
m-3.

9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex