Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On $^{146}$Nd, $^{144}$Sm and other unexplored 2$\beta$ decay isotopes   $^{146}$Nd is one of only four (over a total of 35 existing) 2$\beta^-$ decay
isotope candidates whose half-lives currently lack experimental limits. The
$\alpha$ activity of the $^{146}$Sm daughter nuclide allows placement of limits
on the 2$\beta$ decay using the $^{146}$Nd/$^{142}$Nd abundance ratio
($T^{\beta\beta}_{1/2} \gsim 3 \times 10^9$ yr) or direct search for $^{146}$Sm
with accelerator mass spectrometers ($T^{\beta\beta}_{1/2} \gsim 4.5 \times
10^{19}$ yr). With a similar approach, a modest ($\sim$ Gyr) first limit on
half-lives for the other unexplored $2\beta$ unstable isotopes and competitive
limits (few $10^{13}$yr) for $^{98}$Mo and $^{122}$Sn are also given. Finally,
it is shown how the limit $T^{0\nu\epsilon\beta^+}_{1/2} \gsim 10^{15}$ yr for
the unexplored $^{144}$Sm $0\nu\epsilon \beta^+$ decay may be obtained from the
data of a GSO crystal scintillator.

33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: alg-geom
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg