http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Determination of the S factor of ¹¹C(p,γ)¹²N from ¹⁴N(¹¹C,¹²N) ¹³C
xvii, 112 leaves : illustrations ; 28 cm.
The quasar is one of the earliest known structures ever to form in the universe. A supermassive star with low metallicity, M > 10⁵ M[sun], Z<0.005 (Population III), is a plausible explanation for the quasar core. But its fate is poorly understood since it lacked CNO nuclei that would have supported it against stellar collapse. The evolution of these supermassive stars could be changed by the updated reaction sequences suggested by Wiescher and others. The ¹¹C(p,γ)¹²N reaction, which, according to their results, occurs when 0.2<T₉<0.4, is an important branch point in the Rapid Alpha Proton capture (rap) sequences. Up to now, only one experiment has studied this reaction via ¹²N Coulomb breakup. From their results, they concluded that the main contribution to ¹¹C(p,γ)¹²N in the interesting region below T₉=0.3 comes from direct capture and above this temperature from the resonant population of the first excited state. In our experiment, a 110 MeV ¹¹C radioactive beam was used to study the ¹⁴N(¹¹C,¹²N)¹³C peripheral transfer reaction. The asymptotic normalization coefficients for ¹²N<->¹¹C+p were extracted from the measured cross section. These coefficients were used to determine the direct capture rate with better precision. The contribution of the second resonance was re-estimated using an R-Matrix approach with the new ANCs and latest [][γ]. We find the S factor for ¹¹C(p,γ)¹²N to be significantly larger than the previous estimates. As a result, the rap II and III processes will occur at lower density, thus increasing the probability for a supermassive star explosion.
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Includes bibliographical references (leaves 108-110).