Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Phonon Absorption at the Magneto-Roton Minimum in the Fractional Quantum
  Hall Effect   We have made the first phonon absorption measurements in the fractional
quantum Hall r\'egime. Experiments have been conducted on two samples which
have similar electron densities but greatly differing mobilities. The energy
gaps as measured by activation studies of the longitudinal resistance differ by
a factor of two. Phonon absorption measurements give almost identical values
for the energy gap demonstrating that the gap measured in this way is rather
insensitive to disorder. The value of this gap is in agreement with the
activation gap measured in the high mobility sample. Values obtained at
$\nu=2/3$ are in good agreement with theory.

5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an