Neutrino Physics
The Standard Model of Particle Physics The Higgs Quarks make up stuff
Force particles
Charged leptons
Neutrinos
3 generations of matter particles Neutrino Properties Electrically neutral
Very very small mass (but non-zero)
They are the most common particle in the universe
The Big Bang Accelerators and Reactors 20 The Sun 10 ν/s 11 2 300 /cm3 10 /cm /s
Neutrino Sources
Cosmic Rays Radioactive decay Astrophysics 2 (Supernovae) 1 ν/cm /s in the earth 106 ν/cm2/s Neutrino Properties Electrically neutral
Very very small mass (but non-zero)
They are the most common particle in the universe
They only interact through the weak interaction
To a neutrino a planet is just a wisp of fog
Roughly 100 trillion go through you every second
You can never detect the neutrinos - just what they do when they interact in our detectors. # Neutrino Detections =
Probability of a neutrino to interact
Flux of neutrinos ×
Number of target atoms
Detectors need to be big...
...very big
...very big
Neutrinos : Particles In Disguise
Neutrinos are relaxed about identity. They can change type as they propagate from point to point.
They can only do this if they have mass. e Long journey e
e
e distance
1
e ν μ s i t I
. b ν e o r P
0 Distance Travelled T2K : A neutrino flavour oscillation experiment
295 km e
Why study them?
Neutrinos are cool...
Why study them?
Why study them?
Why is the universe dominated by matter and not anti-matter?
The way neutrinos (and anti-neutrinos) change flavour could help answer this question.
Summary
Neutrinos are cool!
"The chances of a neutrino actually hitting something as it travels through all this howling emptiness are roughly comparable to that of dropping a ball bearing at random from a cruising 747 and hitting, say, an egg sandwich."
Douglas Adams-Mostly Harmless
The chances of this happening is about 1 part in 1014
Matter
light
Anti-Matter 2 E = mc Matter
light
Anti-Matter
The reverse reaction should also happen with the same probability Equal amounts of matter and antimatter
1 atom of matter to 0.0000000001 atoms of antimatter It's Quantum.....
3 |ν >= U |ν > where U is a unitary matrix α ∑i=1 αi i i
i( Ek t − pk x) 2 |νk (t,x )>=e |νk (0,0)> → P(ν α(0,0)→ν β (t,x ))=|< νβ(t,x )|να (0,0)>|
2 * * i E E t p p x |< t,x | 0,0 >| U U U U e (( j − k) −( j− k) ) νβ( ) να ( ) =∑k ∑ j α k α j β k β j
E E t p p x p2 m2 p2 m2 x p p x= ( j − i ) −( j− i) =(√ j + j −√ i + i ) −( j − i)
2 2 2 1 m j 1 mi Δ mij ( p j (1+ )−pi (1+ ))≈ 2 p j 2 pi 4E
2 cosθ sin θ 2 2 Δ m12 L U = P(ν α (0,0)→ν β(t,x ))=sin (2θ) sin ( ) (−sin θ cosθ) 4E