Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Performance of the PrimEx Electromagnetic Calorimeter   We report the design and performance of the hybrid electromagnetic
calorimeter consisting of 1152 $PbWO_4$ crystals and 576 lead glass blocks for
the PrimEx experiment at the Jefferson Laboratory. The detector was built for
high precision measurement of the neutral pion lifetime via the Primakoff
effect. Calorimeter installation and commissioning was completed with the first
physics run in fall of 2004. We present the energy and position resolution of
the calorimeter. Obtained $\pi^0$ mass resolution of $1.3 \mathrm{MeV/c^2}$ and
its production angle resolution of $0.34 \mathrm{mrad}$ demonstrate the ability
of the experiment to extract the $\pi^0$ lifetime on one percent level.

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The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga