I am not sure if this has been asked recently, but has there been any headway into solving the solar neutrino problem? I recently completed the Particle Physics for non-Physicists by Professor Stephen Pollack. It is from 2006 and I was wondering if the issue had been solved yet.

In it he stated that 66% of the expected neutrinos were being detected. He postulated that the neutrinos could possibly oscillate between types. However wouldn't a tau neutrino and muon neutrino be detected as well?

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    $\begingroup$ Some changed into a different flavour that the experiment couldn't detect. physics.stackexchange.com/q/114176 $\endgroup$ – Martin Beckett May 30 '18 at 21:08
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    $\begingroup$ Has there been progress? There's been a Nobel Prize for resolving the matter. $\endgroup$ – dmckee --- ex-moderator kitten May 30 '18 at 23:18
  • $\begingroup$ Did you consider even searching online for your title? The first link I see is a Wikipedia article of the same name which gives you your answer in the introduction... $\endgroup$ – Kyle Kanos May 31 '18 at 0:55
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    $\begingroup$ @dmckee Well deserved, too. Accelerator physics is blowing up world wide, and Ray Davis in a mine in South Dakota complaining there are only 26 argon atoms in my swimming pool per month, and there should be 40. $\endgroup$ – JEB May 31 '18 at 6:54
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    $\begingroup$ I'm voting to close this question as off-topic because of lack of prior research. $\endgroup$ – Emilio Pisanty Jun 6 '18 at 11:42

However wouldn't a tau neutrino and muon neutrino be detected as well?

Yes, and an experiment that led to a Nobel prize was done

. All of the solar neutrino detectors prior to SNO had been sensitive primarily or exclusively to electron neutrinos and yielded little to no information on muon neutrinos and tau neutrinos.

In 1984, Herb Chen of the University of California at Irvine first pointed out the advantages of using heavy water as a detector for solar neutrinos.Unlike previous detectors, using heavy water would make the detector sensitive to two reactions, one reaction sensitive to all neutrino flavours, the other reaction sensitive to only electron neutrino. Thus, such detector can measure neutrino oscillations directly.


On 18 June 2001, the first scientific results of SNO were published, bringing the first clear evidence that neutrinos oscillate (i.e. that they can transmute into one another), as they travel in the sun. This oscillation in turn implies that neutrinos have non-zero masses. The total flux of all neutrino flavours measured by SNO agrees well with the theoretical prediction. Further measurements carried out by SNO have since confirmed and improved the precision of the original result.

Italics mine.


Most experiments cannot detect muon or tau neutrinos at solar neutrino energies.

The easiest way to detect a neutrino is via a charged current interaction, such as: $$\rm\bar{\nu_e}+p\to e^++n $$

The critical thing here is that that process is only possible if the energy of the neutrino is enough to create the corresponding lepton. Solar neutrinos can have enough energy to produce an electron, but not a muon or a tau lepton.

Neutral current interactions are also possible, but much more difficult to detect for low energy neutrinos. So for most purposes neutrinos besides electron neutrinos from the sun are totally invisible.


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