1. Super-Kamiokande and Neutrino Oscillation
Good evening . Thanks for giving chance of talk to me.
First, let me introduce my subject. My subject is neutrino physics and super-kamiokande.
So this evening I will show you why neutrino mass is so important and how super-kamiokade
proved the existence of neutrino mass.
Hui-Young Ryu
Pusan National University

2. Contents Ⅰ. Motivation Ⅱ. Theoretical Background Ⅲ. Experiment
Ⅳ. Data Review
Ⅴ. Summary
My talk sequence is like this..

3. Ⅰ. Motivation 1. Solar neutrino problem
A lot of electron neutrinos are produced as a result
of nuclear fusion in the Sun. The number of neutrinos
at the Earth is But measured neutrinos
are only 40 % of them. catch only 40% of them…
First of all, I want to introduce how people have been so interested in neutrino.
Actually there are many interesting subjects, here I will introduce two famous
problem.
The first famous thing is solar neutrino problem
(……)
Why ?

4. 2. Cosmic Ray neutrino ratio
Theoretical Expectaion :
In the atmosphere,
Measurement :
On the Earth
Next cosmic ray neutrino ratio
In the atmosphere, cosmic ray collides with the nucleus
in the atmosphere. This event causes the
plenty creation of neutrinos and our calcul-
ation expect that the ratio of and is
1 to 2.
Why ?

5. Ⅱ. Theoretical Background
1. Brief summary of neutrino history
1.1 The neutrino hypothesis
There exists a neutral, spin ½ particle which is
simultaneously emitted with the electron in beta-decay.
This hypothesis resolves the following difficulties
(1) The apparent non-conservation of
energy in beta-decay
(2) The apparent non-conservation of
angular momentum in certain beta-decay
Before we attack this problems, I will review brief summary of neutrino.
At first, in 1932 Pauli suggested the neutrino hypothesis to solve the
Non-conservation of mass and non-conservaiton of angular momentum
In beta decay. The neutrino hypothesis is as following.

6. 1.2 Two kinds of beta-decay
(Example)
(Example)
There are two kinds of beta-decay
Beta plus decay is proton number minus process.
And as a result, positron and electron neutrino are produced.
On the other hand, beta minus decay is proton number plus process.
In this process, electron and anti-neutrino are produced.

7. 1.3 Fermi’s Beta-decay theory
When Fermi in 1933 considered beta-decay, he
thought that the electron and neutrino can be created
Within range due to uncertainty principle,
His theory was very successful in leading-order, but
divergent in next-to-leading-order.
(Fermi assumed that mass of neutrino is zero)

8. 1.4 Experimental evidence of existence of
In present, we think there are three neutrinos:
muon neutrino, electron neutrino and tau neutrino.
The electron neutrino was found in The muon
neutrino was found in The tau neutrino have
not directly found yet. But there are many indirect
evidence of existence of tau neutrino.

9. 2. Neutrino Oscillation
Neutrino oscillation is the key to determine whether
the neutrino mass is zero or not. If a neutrino mass is
not zero, neutrino can be changed to other neutrino
(by neutrino oscillation), and this phenomena can solve
the solar neutrino problem and cosmic ray neutrino
problem.
Neutrino oscillation is somewhat old idea which explains the transition of particles.

10. In electro-magnetic theory, neutrinos propagate through
space as a superposition of mass eigenstates
From the above, we can express

11. From the oscillation idea, we can derive
where
Because is very small, is
almost near to 1for small L. But if L is large enough,
can be non-zero.
From the oscillation idea, we can derive….
P(mu->mu) means the probability of muon neutrino translate to own
And P(mu->e) means the probability of muon neutrino change to electron neutrino.
Both of them are dependent of the distance of traveled

12. We can describe this idea by using plot. From the
previous equations, we can get
Now we assume neutrino behavior as a plan wave, i.e.
Then ,with initial conditions, we can get

13. It is easy to get the following results by the previous equations
To make the equation simple , for
(….) we can choose the parameter to best fit

14. When the phase difference is
From the above result, we can plot
When the phase difference is zero,
There is only muon neutrino
On the other hand, if the phase difference is pi,
There is no muon neutrino
We can describe this situation by two mass eigenstates
phase

15. So if we compare the ratio to the theoretical
value, we would know that the neutrino mass is zero
or not. That is what the Super-Kamiokande did

16. Ⅲ. Experiment 1. Super Kamiokande - Overview
Size : Cylinder of 41.4m(Height), 39.3m(Diameter)
Weight : 50,000 tons of pure water
Light Sensitivity : 11,200 PMT (50cm each in
diameter - the biggest size in the world)
(They are very sensitive light detectors and they can detect
single photons. They are looking into the the inner volume of water)
4) Location : Kamioka-cho, Yoshiki-gun (1,000m
underground at the Mozumi mine)
Next let’s consider how to experiment.
It is brief summary of super-kamiokande

17. 2. Outside and Inside

18. 3. Sequence of process Cosmic ray In the S-K 2 muon neutrinos and
1 electron neutrino
In the S-K
A neutrino interact with water
An electron produces Cerenkov light
PMTs count the numbers of neutrino

19. Ⅳ. Data Review From the data collected for 500 days in the
Super-Kamiokande, a significant anisotropy was observed in the angular distribution of atmospheric neutrinos. Oscillations of muon neutrinos fit best the observations
<Distributions of lepton zenith angles >
※Blue lines are for distributions expected without oscillations,
red - with the best fit oscillation parameters.

20. The Nobel Prize in Physics 2002
" for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos"
"for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources"
Raymond Davis Jr.
Masatoshi
Koshiba
Riccardo
Giacconi
¼ of the prize
USA
¼ of the prize Japan
½ of the prize
University of Pennsylvania Philadelphia, PA,
b. 1914
University of Tokyo Tokyo, Japan
b. 1926
Associated Universities Inc. Washington, DC, USA
b. 1931
(in Genoa, Italy)

21. Ⅴ. Summary ■ Number of neutrino was different form what our
theory expected. (Solar neutrino problem and
cosmic ray neutrino problem, etc.)
■ Neutrino oscillation solved these problems by
assumption of non-zero neutrino mass.
■ From the supernova in 1998 Super-Kamiokande
observed vital evidences of non-zero neutrino
mass.
■ Super-Kamiokande has been used for detecting
proton-decay and its exploration is still going on.