Monday, July 14, 2008

JJNN Monday: Science - 01

Welcome again to JJNN for Monday July 14th, 2008. Today is science day.

This is actually a bit of sad new. You can see the article here. It seems that a great name in science died of colorectal cancer on July 10th at 12:30 pm. His name was Totsuka Youji and he died at the age of 66.

Totsuka Youji a did most of his work in the field of study of neutrinos. I want to give a very quick background on his life. He was born on March 6th 1942, which means he was born during the middle of World War II. He went to school and ended up getting his PhD from Tokyo University in 1972. After he got his PhD he worked his way up in Tokyo University from research associate to associate professor to professor in 1987. As well as his work at Tokyo University he also became the director of the Kamioka observatory and the Institute for Cosmic Ray Research.

Because of Totsuka Youji's work we now know some interesting things about neutrinos. Before we get into what he found out I want to talk a little bit about neutrinos. neutrinos are funny little elementary particles. They travel close to the speed of light and go straight though solid objects without slowing down at all (in most cases). Why do you think that these particles can go though most matter without slowing now? Well the answer is that they are like electrons with no charge so they are not effected by electromagnetic forces. They can only be effected by the weak nuclear force. Weak nuclear forces only act over a short distance so it is more likely neutrinos can mover over long distances without being slowed down.

These particles are made by nuclear decay like that seen in the sun or when high energy solar rays strike atoms. There are 3 different types of neutrinos out there. They are all made by slightly different processes, but I won't go into that. The names of the 3 types are electron neutrinos, tau neutrinos and muon neutrinos. I bet these particles seem exotic and rare, right? Well, the fact of the matter is that according to this about 50 trillion of these particles go though any human being.

Those are interesting facts, but what Totsuka Youji found out about neutrinos is even more interesting. First, he is the person that found out that the neutrino has a very small, yet detectable, mass. Before it was thought that these particles did not have a mass and it was sort of like light, but he helped to prove that theory was not true. Second, he helped to prove that while neutrinos are moving though space they turn into different types of neutrinos and turn back again. Both of those discoveries are pieces of information that will help us to know more about the neutrino and other things in the universe.

Before going onto the word of the day I want to talk about how we know that neutrinos exist in the first place. Like I said before, neutrinos do not play well with other matter (by the fact that they go though it), so how can we detect neutrinos in the first place. Well even though the neutrino goes though most materials, if it goes though enough stuff it is bound to hit something because of probability alone. So, a good neutrino detector is one in which there is enough of a substance that is isolated from things like cosmic rays and constantly watched for an interactions. Super Kamiokande in Japan uses a lot of water that is surrounded by phototubes that will pick up the Cherenkov radiation given off by the neutrino when it collides with something. Other detectors use different materials.

Any way, it is now time for the word of the day. Today's word is ニュートリノ(にゅうとりの). It is pronounced nyuutorino and means neutrino. I remember the first time I heard about neutrinos and the fact that there are so many of them going though our bodies every second of every day. That is probably one of the things that really made me want to study science (thanks Nova).

That's it for today. See you next time at JJNN.

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