Measurements of1H(d→,γ)3

Estimating reaction rates and uncertainties for primordial nucleosynthesis

“…These numbers have not found their way into all subsequent work (e.g., Ref. [22]), and we know of no calculations that have incorporated either of the recent TUNL measurements of the d(p, γ) 3 He [15,16] cross section (save one reported in this last experimental reference). One of our goals is to provide a new standard calculation which incorporates these measurements so that they are not ignored in future theoretical work.…”

“…However, it is encouraging that our splines indicate much the same energy dependence as the microscopic calculation [36,16], so the sparseness is probably not such a big problem. Our errors reflect the ∼ 8% normalization errors in the best measurements of the cross section.…”

“…This was a landmark work because it examined all the nuclear inputs critically and in detail, and it placed quantitative error estimates on all the inputs. There has been a small number of new cross section measurements since [14][15][16][17], which have been unevenly incorporated in subsequent work. Subsequent authors have continued to use the SKM rates and errors for most or all reactions.…”

Primordial Nucleosynthesis

“…We chose the second option, with Marcucci et al [20] [D(p,γ) 3 He] and Arai et al [21] [D(d,n) 3 He and D(d,p) 3 H] as theoretical S -factors, keeping the normalization (α) as a free parameter that has to be determined by comparison with experimental data. The procedure we followed [5] for the D(p,γ) 3 He reaction was i) to select experimental datasets [22][23][24][25] for which systematic uncertainties were provided, ii) determine for each data set, by χ 2 minimization, the normalization factor to be applied to the theoretical S -factor of Marcucci et al [20], iii) add quadratically the systematic uncertainties and iv) perform a weighted average of the normalization factor. We obtained α = 0.9900 ± 0.0368 for this factor, that was subsequently used to scale the Marcucci et al S -factor, and calculate the thermonuclear D(p,γ) 3 He reaction rate and associated uncertainty.…”

“…2. Ratio of experimental [22][23][24][25], fitted [5,[27][28][29] and new theoretical [30] S -factors to the theoretical one [20]; the horizontal lines correspond to the theoretical S -factor scaled by α ± ∆α [5]. (Systematic uncertainties in the range 4.5-9% are not shown.…”