Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rhodium Mossbauer Superradiance of Observable Gravitational Effect   We summarize the experimental observations of three case studies on the
long-lived rhodium Mossbauer Effect. Extraordinary observations reported in
this work manifest the open-up of photonic band gap in analogy to the
superconducting gap. Observable gravitational effect is manifested by the
superradiance of different sample orientations corresponding to the earth
gravity. These observations are of potential importance for detecting
gravitational waves and development of the two-photon gamma laser.

2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
16
The categories of this paper are: stat
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat