Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observations of Microwave Continuum Emission from Air Shower Plasmas   We investigate a possible new technique for microwave measurements of
ultra-high energy cosmic ray (UHECR) extensive air showers which relies on
detection of expected continuum radiation in the microwave range, caused by
free-electron collisions with neutrals in the tenuous plasma left after the
passage of the shower. We performed an initial experiment at the AWA (Argonne
Wakefield Accelerator) laboratory in 2003 and measured broadband microwave
emission from air ionized via high energy electrons and photons. A follow-up
experiment at SLAC (Stanford Linear Accelerator Center) in summer of 2004
confirmed the major features of the previous AWA observations with better
precision and made additional measurements relevant to the calorimetric
capabilities of the method. Prompted by these results we built a prototype
detector using satellite television technology, and have made measurements
indicating possible detection of cosmic ray extensive air showers. The method,
if confirmed by experiments now in progress, could provide a high-duty cycle
complement to current nitrogen fluorescence observations of UHECR, which are
limited to dark, clear nights. By contrast, decimeter microwave observations
can be made both night and day, in clear or cloudy weather, or even in the
presence of moderate precipitation.

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The categories of this paper are: math-ph
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The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
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The categories of this paper are: chem-ph
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: solv-int
1
The categories of this paper are: cs
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: nlin
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The categories of this paper are: ao-sci