Raymond Davis Jr.

Exactly.

And to look through that window, a physicist named Raymond Davis Jr. built a massive detector in the 1960s.

He went deep underground into the Homestake gold mine in South Dakota.

Using the miles of rock overhead to shield his experiment from cosmic rays and background radiation.

In 2013, the research team reported the first evidence to support that they really had found cosmic neutrinos, and a couple of years later, they gathered so much data they could be certain of their discovery.

Neutrino astronomy started on a small scale back in the 1960s when Raymond Davis Jr. observed neutrinos from the sun.

This was confirmed by the research team at the Kamiokande Neutrino Observatory in Japan, led by Masatoshi Koshiba, as they were able to determine the neutrinos' path and trace their origin.

In 1987, Kamiokande captured a shower of neutrinos that could be linked to an exploding star, a supernova, in the Large Magellanic Cloud, which is our neighboring galaxy.

Raymond Davis Jr. and Masatoshi Koshiba were awarded the Nobel Prize in Physics in 2002 for these breakthroughs, which demonstrated that neutrinos could be used to study phenomena in space.

The path of protons in space is curved by the magnetic fields they travel through because of their charge, making it impossible to track the direction they took.

However, the processes that accelerate the protons will also produce neutrinos, which are not affected by magnetic fields, so it should be possible to work out where the cosmic ray protons are accelerated by tracing back along the straight line path of the highest energy neutrinos.

Okay.

And one of the famous experiments done by the, the Nobel Prize winners that discovered the neutrinos, Raymond Davis, he discovered that, you know, there's only a third of the neutrinos that we see from the sun showing up in my detector.

Hmm.

Right?

Great invention there, Yosef.

We also remember Nobel Prize winning American chemist and physicist Raymond Davis born 100, oh, junior, sorry, Raymond Davis Jr.

You can call me Ray or you can call me Jay.

Remember that sketch? Yes, I do remember that.

It also fits a lineage.

Raymond Davis and Masatoshi Koshiba shared a Nobel in 2002 for catching neutrinos from the sun, and from Supernova 1987A, the explosion in the Large Magellanic Cloud we talked about just a few weeks ago, still the only supernova whose neutrinos we've ever detected.

In 2015, it was Takaaki Kajita and Arthur McDonald for showing neutrinos change flavor.

The next step is bigger ice.

Up until about the year 2000, um, we thought there were three types of neutrinos and those are three different particles.

Um, there was an ongoing mystery in, um, an experiment conducted by someone called Ray Davis, um, which was one of these Nobel Prizes that we'd talked about, um, who was measuring neutrinos produced in the sun.

Um, and the reason he was doing that actually was not to study neutrinos, but rather to study the sun.

Um, there were different models of what was going on in the sun at the time, and people realized that, uh, you know, the various nuclear reactions that were happening inside the sun would produce neutrinos, and those neutrinos would come to Earth and we could measure them, and then we could test these models.

Um, but it was discovered by two experiments, um, around the year 2000, I think Super-Kamiokande in 1998 and SNO+ in Canada in 2001, um, that actually what is happening is much more interesting.

And so neutrinos, uh, being produced in the sun are all electron neutrinos because of the types of nuclear reactions that produce them.

Um, and Ray Davis' experiment looked for electron neutrinos, and he only saw half the amount that he expected to see.

Um, what SNO+ showed is that if you measure all three types of neutrinos, you actually do get the correct amount.