Neutrinos from the sun

The answer to the solar neutrino problem lies in the fact that there are multiple neutrino flavors.

Imagine you are lying (or frying) on a beach near the equator at midday. Feel the heat! It is 1.37 kilowatts per square meter. That is 1.04 kilowatts per square yard, but please, get used to the metric system — much easier than units based on the length of King John’s foot or the distance from King Henry’s nose to his outstretched thumb. The only countries in the world still clinging to that archaic system are Liberia, Myanmar and the United States, while the UK is letting go.

If you have solar panels to generate electricity, you use electromagnetic radiation from the sun. It comes from nuclear fusion reactions deep inside, and physicists have known for 80 years how that works. For 50 years, scientists have been trying to make a nuclear fusion machine to generate more electricity than it uses. In my opinion, that may never happen.

A hydrogen bomb releases fusion energy, catastrophically. The sun is pretty steady, always there, and at a safe distance, about 150 million kilometers. A cubic meter of the center of the sun actually generates less than 100 watts … WHAT! But that means 100 billion watts, or 100 gigawatts, per cubic kilometer, and the sun is very big. (That calculation was so much easier in metric than using yards and miles, right?)

In my last column, I said that scientists had detected ghostly particles called neutrinos coming from nuclear reactions in the sun, but that there was a puzzle. In a huge tank of dry-cleaning fluid, neutrinos transformed about three chlorine atoms into argon per week. But it should have been about three times more.

At last we know why. There are three different types of neutrinos. One is called “electron type,” and only that type is emitted from reactions in the sun, and only that type can turn chlorine into argon. A second type was discovered by Leon Lederman, past director of Fermilab, and in 2000 the third type was discovered here.

Mysteriously, neutrinos are “transtype,” like shapeshifters. A neutrino of one type becomes a mixture of all three. Very strange. Fermilab is studying how this happens.

This is a version of an article that first appeared in Positively Naperville.