# How many $pep$-related electron-neutrinos $\nu_e$ does the Sun produce?

In the sun neutrinos can be produced by the rare proton-electron-proton (pep) reaction:

$${}^1_1 H + e + {}^1_1 H \to {}^2_1 H + \nu_e$$

How many pep-related electron neutrinos does the Sun produce?

• The Standard solar model might help Commented Feb 21, 2020 at 10:40
• I assume you mean the neutrino production rate, that is, how many are produced in one second, for example? Commented Feb 22, 2020 at 0:04

We observed, for the first time, solar neutrinos in the 1.0-1.5 MeV energy range. We measured the rate of pep solar neutrino interactions in Borexino to be [3.1$$\pm$$0.6(stat)$$\pm$$0.3(syst)] counts/(day x 100 ton) and provided a constraint on the CNO solar neutrino interaction rate of < 7.9 counts/(day x 100 ton) (95% C.L.). The absence of the solar neutrino signal is disfavored at 99.97% C.L., while the absence of the pep signal is disfavored at 98% C.L. This unprecedented sensitivity was achieved by adopting novel data analysis techniques for the rejection of cosmogenic $$^{11}$$C, the dominant background in the 1-2 MeV region. Assuming the MSW-LMA solution to solar neutrino oscillations, these values correspond to solar neutrino fluxes of [1.6$$\pm$$0.3]$$\times 10^8$$ cm$$^{-2}$$s$$^{-1}$$ and 7.7$$\times10^8$$ cm$$^{-2}$$s$$^{-1}$$ (95% C.L.), respectively, in agreement with the Standard Solar Model. These results represent the first measurement of the pep neutrino flux and the strongest constraint of the CNO solar neutrino flux to date.
$$\frac{dN}{dt} = \phi A = 1.6\times 10^{12}\: \mathrm{m}^{-2}\mathrm{s}^{-1} \times 4\pi\times (1.5 \times 10^{11} \:\text{m})^2 \approx \underline{4.5 \times 10^{35} \: \mathrm{s}^{-1}}$$