Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Is \gamma-ray emission from novae affected by interference effects in
  the 18F(p,\alpha)15O reaction?   The 18F(p,\alpha)15O reaction rate is crucial for constraining model
predictions of the \gamma-ray observable radioisotope 18F produced in novae.
The determination of this rate is challenging due to particular features of the
level scheme of the compound nucleus, 19Ne, which result in interference
effects potentially playing a significant role. The dominant uncertainty in
this rate arises from interference between J\pi=3/2+ states near the proton
threshold (Sp = 6.411 MeV) and a broad J\pi=3/2+ state at 665 keV above
threshold. This unknown interference term results in up to a factor of 40
uncertainty in the astrophysical S-factor at nova temperatures. Here we report
a new measurement of states in this energy region using the 19F(3He,t)19Ne
reaction. In stark contrast with previous assumptions we find at least 3
resonances between the proton threshold and Ecm=50 keV, all with different
angular distributions. None of these are consistent with J\pi= 3/2+ angular
distributions. We find that the main uncertainty now arises from the unknown
proton-width of the 48 keV resonance, not from possible interference effects.
Hydrodynamic nova model calculations performed indicate that this unknown width
affects 18F production by at least a factor of two in the model considered.

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The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
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The categories of this paper are: adap-org
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The categories of this paper are: hep-lat
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The categories of this paper are: eess
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The categories of this paper are: chem-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: nlin
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The categories of this paper are: bayes-an
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: funct-an