Background: The He3(α,γ)Be7 reaction is of critical importance in determining the flux of solar neutrinos through the pp-II and pp-III chains. For this reason and others, the description of the cross section and its extrapolation towards low-energy has always been a matter of intense debate. While large systematic differences have been present in the past, several recent measurements are all in excellent statistical agreement. Purpose: The convergence of the recent individual experimental measurements of the He3(α,γ)Be7 reaction prompts a global analysis of the reaction data. From the combined data, a more precise estimate of the low-energy cross section can be determined. Results: A global R-matrix fit is used to describe the He3(α,γ)Be7 data as well as scattering data over a similar energy range. The R-matrix fit is then subjected to a Monte Carlo analysis to extract the uncertainties on the cross section and corresponding reaction rate. Conclusion: By combining several recent measurements of the He3(α,γ)Be7 reaction, the combined data yield a zero energy S factor of S(0)=0.542±0.011(MCfit)±0.006(model)+0.019−0.011(phaseshifts) keV b. This gives a total uncertainty in S(0) of +0.023/−0.017 keV b.
Monte Carlo uncertainty of the H3(alpha, gamma)B7 reaction rate / R. J., Deboer; J., Gores; K., Smith; E., Uberseder; M., Wiescher; A., Kontos; Imbriani, Gianluca; DI LEVA, Antonino; F., Strieder. - In: PHYSICAL REVIEW. C, NUCLEAR PHYSICS. - ISSN 0556-2813. - 90:(2014), pp. 35804-35815. [10.1103/PhysRevC.90.035804]
Monte Carlo uncertainty of the H3(alpha, gamma)B7 reaction rate
IMBRIANI, GIANLUCA;DI LEVA, ANTONINO;
2014
Abstract
Background: The He3(α,γ)Be7 reaction is of critical importance in determining the flux of solar neutrinos through the pp-II and pp-III chains. For this reason and others, the description of the cross section and its extrapolation towards low-energy has always been a matter of intense debate. While large systematic differences have been present in the past, several recent measurements are all in excellent statistical agreement. Purpose: The convergence of the recent individual experimental measurements of the He3(α,γ)Be7 reaction prompts a global analysis of the reaction data. From the combined data, a more precise estimate of the low-energy cross section can be determined. Results: A global R-matrix fit is used to describe the He3(α,γ)Be7 data as well as scattering data over a similar energy range. The R-matrix fit is then subjected to a Monte Carlo analysis to extract the uncertainties on the cross section and corresponding reaction rate. Conclusion: By combining several recent measurements of the He3(α,γ)Be7 reaction, the combined data yield a zero energy S factor of S(0)=0.542±0.011(MCfit)±0.006(model)+0.019−0.011(phaseshifts) keV b. This gives a total uncertainty in S(0) of +0.023/−0.017 keV b.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.