The standard solar model's predicted rate and the measured rate are given for three…

PHYSICS · Multi-part · Fermi University Physics · Particle Physics & Quantum Fields · Astrophysics & Cosmology · Stellar structure, energy generation and evolution

Stars from the Inside, Ch The Sun as a test: calibration, sound, neutrinos and a magnetised atmosphere

Problem

The standard solar model's predicted rate and the measured rate are given for three solar neutrino detectors. Data (detector, threshold, predicted, measured): Chlorine (Homestake),

0.814\,\mathrm{MeV}

7.6\,\mathrm{SNU}

2.56\,\mathrm{SNU}

; Gallium (GALLEX/SAGE),

0.233\,\mathrm{MeV}

128\,\mathrm{SNU}

66\,\mathrm{SNU}

; Water Cherenkov (Kamiokande,

^8

B scattering off electrons), threshold

\approx5\,\mathrm{MeV}

5.05\times10^{6}\,\mathrm{cm^{-2}\,s^{-1}}

2.80\times10^{6}\,\mathrm{cm^{-2}\,s^{-1}}

. ((a)) Compute the ratio (measured/predicted) for each of the three detectors. ((b)) Chlorine's threshold excludes the pp neutrinos and leaves mainly beryllium-7 and boron-8; gallium's admits the pp neutrinos as well; the water detector counts only boron-8 neutrinos, by scattering off electrons, with a smaller sensitivity to the other flavours. Suppose the electron neutrinos of every branch arrived short by one common factor. How would the chlorine and gallium ratios then compare? What do the measured ratios say about the pp neutrinos, and why can the water ratio sit above chlorine's although boron-8 dominates both?

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