Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: TAU-4 installation intended for long-term monitoring of a half-life
  value of the $^{212}$Po   Description of the TAU-4 installation intended for long-term monitoring of
the half-life value $T_{1/2}$ of the $^{212}$Po is presented. Natural thorium
used as a source of the mother's chain. The methods of measurement and data
processing are described. The comparative results of short test measurements
carried out in the ground (680 h) and underground (564 h) laboratories are
given. Averaged value $T_{1/2}$ =$294.09\pm 0.07$ ns of the $^{212}$Po
half-life has been found for the ground level data set similar one for the
underground data set. The solar-daily variations with amplitudes
$A_{So}=(11.7\pm 5.2)\times10^{-4}$ for the ground data and $A_{So}=(7.5\pm
4.1)\times10^{-4}$ for the underground one were found in a series of $\tau$
values.

29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int