Make the Sun your neutrino source

1 · Recover the pp flux from the Sun's brightness

Borexino and SNO measure the ⁷Be, CNO and ⁸B neutrinos. The most numerous ones, the pp neutrinos, are missing.

Beginner

Why use the Sun as the source, rather than a new radioactive source?

Because gallium detectors had never observed the Sun before Because its neutrino flux is measured by Borexino and SNO, without going through the gallium cross-section Because solar neutrinos arrive without changing flavour

2 · Switch the Sun on, source by source

Intermediate

Source experiments see 0.817 of the expected rate. If the Sun showed the same shortfall, how many SNU would the detectors have measured?

About 66 SNU, what they measured About 83 SNU About 55 SNU

3 · Test Cadeddu's hypothesis

Cadeddu and colleagues propose a cross-section 20% lower. Your slider applies it to the sources' expected rates and to the whole solar prediction, more than 90% of which rests on it.

Expert

With a cross-section 20% lower, where would the solar point, now at 0.980, land?

Near 0.78: the Sun would show a shortfall in turn Near 1.22: gallium would catch more solar neutrinos than predicted Still near 0.980: only the sources' prediction depends on the cross-section

4 · Give gallium its cross-section back

Expert

The Sun confirms the extraction and counting of germanium in the solar runs. What about the source experiments?

Probably accurate too: their procedures are similar Accurate, since BEST sees no dependence on distance Under suspicion: they are the only suspects the Sun cannot test

Solar test redone

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