Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of a Universal Aggregation Mechanism and a Possible Phase
  Transition in Au Sputtered by Swift Heavy Ions   Two exponents, $\delta$, for size distribution of $n$-atom clusters,
$Y(n)\sim n^{-\delta}$, have been found in Au clusters sputtered from embedded
Au nanoparticles under swift heavy ion irradiation. For small clusters, below
12.5 nm in size, $\delta$ has been found to be 3/2, which can be rationalized
as occurring from a steady state aggregation process with size independent
aggregation. For larger clusters, a $\delta$ value of 7/2 is suggested, which
might come from a dynamical transition to another steady state where
aggregation and evaporation rates are size dependent. In the present case, the
observed decay exponents do not support any possibility of a thermodynamic
liquid-gas type phase transition taking place, resulting in cluster formation.

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The categories of this paper are: atom-ph
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th