http://arxiv.org/abs/1602.05911
The $^9$Be$(\gamma,n)^8$Be reaction is enhanced by a near threshold $1/2^+$ state. Contradictions between existing measurements of this reaction cross-section affect calculations of astrophysical r-process yields, dark matter detector calibrations, and the theory of the nuclear structure of $^9$Be. Select well-documented radioisotope $^9$Be$(\gamma,n)$ source yield measurements have been reanalyzed, providing a set of high-accuracy independently measured cross sections. A Breit-Wigner fit of these corrected measurements yields $E_R=1738.8^{+5.0}_{-4.2}$~keV, $\Gamma_\gamma=0.771^{+0.055}_{-0.044}$~eV, and $\Gamma_n=268^{+40}_{-33}$~keV for the $1/2^+$ state. The fit favors a resonant $1/2^+$ state, but a virtual state is not excluded.
A. Robinson
Fri, 19 Feb 16
40/50
Comments: 7 pages, 4 figures, 4 tables
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