A compilation of charged-particle induced thermonuclear reaction rates

Thermonuclear reaction rates V

For interpreting fusion rate measurements in present fusion experiments and predicting the fusion performance of future devices or of d-t experiments in present devices, it is important to know the fusion cross-sections as precisely as possible. Usually, it is not measured data that are used, but parametrizations of the cross-section as a function of the ion energy and parametrizations of the Maxwellian reactivity as a function of the ion-temperature. Since the publication of the parametrizations now in use, new measurements have been made and evaluations of the measured data have been improved by applying R-matrix theory. The authors show that the old parametrizations no longer adequately represent the experimental data and present new parametrizations based on R-matrix calculations for fusion cross-sections and Maxwellian reactivities for the reactions D(d,n)3He, D(d,p)T, T(d,n)4He and 3He(d,p)4He

https://iopscience.iop.org/article/10.1088/0029-5515/32/4/I07/pdf

Improved formulas for fusion cross-sections and thermal reactivities

Big bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) have a long history together in the standard cosmology. BBN accurately predicts the primordial light element abundances of deuterium, helium and lithium. The general concordance between the predicted and observed light element abundances provides a direct probe of the universal baryon density. Recent CMB anisotropy measurements, particularly the observations performed by the WMAP satellite, examine this concordance by independently measuring the cosmic baryon density. Key to this test of concordance is a quantitative understanding of the uncertainties in the BBN light element abundance predictions. These uncertainties are dominated by systematic errors in nuclear cross sections, however for helium-4 they are dominated by the uncertainties in the neutron lifetime and Newton's G. We critically analyze the cross section data, producing representations that describe this data and its uncertainties, taking into account the correlations among data, and explicitly treating the systematic errors between data sets. The procedure transforming these representations into thermal rates and errors is discussed. Using these updated nuclear inputs, we compute the new BBN abundance predictions, and quantitatively examine their concordance with observations. Depending on what deuterium observations are adopted, one gets the following constraints on the baryon density: ${\ensuremath{\Omega}}_{\mathrm{B}}{h}^{2}=0.0229\ifmmode\pm\else\textpm\fi{}0.0013$ or ${\ensuremath{\Omega}}_{\mathrm{B}}{h}^{2}{=0.0216}_{\ensuremath{-}0.0021}^{+0.0020}$ at 68% confidence, fixing ${N}_{\ensuremath{\nu},eff}=3.0.$ If we instead adopt the WMAP baryon density, we find the following deuterium-based constraints on the effective number of neutrinos during BBN: ${N}_{\ensuremath{\nu},eff}{=2.78}_{\ensuremath{-}0.76}^{+0.87}$ or ${N}_{\ensuremath{\nu},eff}{=3.65}_{\ensuremath{-}1.30}^{+1.46}$ at 68% confidence. Concerns over systematics in helium and lithium observations limit the confidence constraints based on this data provide. BBN theory uncertainties are dominated by the following nuclear reactions: ${d(d,n)}^{3}\mathrm{He},$ $d(d,p)t,$ $d(p,\ensuremath{\gamma}{)}^{3}\mathrm{He},$ ${}^{3}\mathrm{He}(\ensuremath{\alpha},\ensuremath{\gamma}{)}^{7}\mathrm{Be}$ and ${}^{3}\mathrm{He}{(d,p)}^{4}\mathrm{He}.$ With new nuclear cross section data, light element abundance observations and the ever increasing resolution of the CMB anisotropy, tighter constraints can be placed on nuclear and particle astrophysics.

Primordial Nucleosynthesis for the New Cosmology: Determining Uncertainties and Examining Concordance

NACRE II: an update of the NACRE compilation of charged-particle-induced thermonuclear reaction rates for nuclei with mass number A < 16

Low-energy fusion cross sections of D + D and D + 3He reactions

Energy determination of heavy-ion beams☆

The reflected beam sputter source

A recoil separator in combination with a windowless gas target has been designed for the measurement of the radiative capture reaction p(7Be, γ)8B. The separator consists of momentum and velocity filters and a ΔE−E detector telescope. The setup was tested quantitatively using the p(12C, γ)13N reaction at the effective energy Ecm = 841 keV. Projectile fluxes were measured directly with Faraday cups and indirectly with elastic backscattering into Si detectors, while the 13N recoil flux was measured directly with the ΔE−E telescope. A suppression of the 12C beam particles by a factor 2 × 10−10 was observed when the system was tuned for the recoil 13N's. Special emphasis was given to the charge state probabilities of the 13N recoils. Possible improvements of the system for the measurement of other capture reactions are discussed.

K. Brand

Papers

Low-energy fusion cross sections of D + D and D + 3He reactions

Energy determination of heavy-ion beams☆

The reflected beam sputter source

A recoil separator for the measurement of radiative capture reactions

Operation results of the Dynamitron Tandem at Bochum