Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effect of damage by 2-MeV He ions on the normal and superconducting
  properties of magnesium diboride   We have studied the effect of damage induced by 2-MeV alpha particles on the
critical temperature, Tc, and resistivity of MgB2 thin films. This technique
allows defects to be controllably introduced into MgB2 in small successive
steps. Tc decreases linearly as the intragrain resistivity at 40 K increases,
while the intergrain connectivity is not changed. Tc is ultimately reduced to
less than 7 K and we see no evidence for a saturation of Tc at about 20 K,
contrary to the predictions of the Tc of MgB2 in the dirty limit of interband
scattering.

33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg