Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the possibility of radar echo detection of ultra-high energy cosmic
  ray- and neutrino-induced extensive air showers   We revisit and extend the analysis supporting a 60 year-old suggestion that
cosmic rays air showers resulting from primary particles with energies above
10^{18} eV should be straightforward to detect with radar ranging techniques,
where the radar echoes are produced by scattering from the column of ionized
air produced by the shower. The idea has remained curiously untested since it
was proposed, but if our analysis is correct, such techniques could provide a
significant alternative approach to air shower detection in a standalone array
with high duty cycle, and might provide highly complementary measurements of
air showers detected in existing and planned ground arrays such as the Fly's
Eye or the Auger Project. The method should be particularly sensitive to
showers that are transverse to and relatively distant from the detector, and is
thus effective in characterizing penetrating horizontal showers such as those
that might be induced by ultra-high energy neutrino primaries.

14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
16
The categories of this paper are: stat
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat