Lisa Falk's presentation about the Neutrino, one of the fundamental particles which make up the universe - Also, currently, one of the least understood. Subatomic particles produced by the decay of radioactive elements. They're special for many reasons - They have no charge, are incredibly light, travel at near light speed and travel through most other matter. Following the introduction to what they are, she detailed the challenges of detecting them (she's been directly involved in these experiments, including time at CERN), and the vast equipment that's used. Finally she talked about the DUNE project, the next stage in Neutrino detection. Presented to Cafe Scientifique, Isle of Wight, 11th May 2015.

1. 12/11/09 E. Falk, U. of Sussex 1
Invisible Neutrinos: The Deep Secrets
of Nature’s Ghosts
Café Scientifique
Shanklin, Isle of Wight
11 May 2015
Elisabeth Falk, University of Sussex

2. 100 trillion neutrinos
passing through each of
our bodies in here...
every second!
That’s 1 followed by 14 zeroes:
100,000,000,000,000
Frightening?

3. Neutrinos are elementary subatomic particles
Atoms make up the matter that we can see:
you, me, the Earth and the stars
Neutrinos are not part of the atoms
– but they are created and destroyed when
atoms are merged (fusion), split (fission) or decay (radioactivity)
Electron
Proton
Neutron
Neutrino
Symbol n
(Greek letter “nu”)
Atom

4. Electron
Proton
Neutron
Neutrino
Symbol n
(Greek letter “nu”)
Atom
Neutrinos
- are among the lightest of the two dozen or so
elementary particles we know
- travel at nearly the speed of light – all the time!
- rarely interact with other matter
- mostly happily zip straight through the Earth

5. The sun (image captured
with ultraviolet light)
The sun (image captured
with neutrinos)
The sun shines because of nuclear fusion in its core
Lighter atomic nuclei merge into heavier ones
Produces light and neutrinos! + light!

6. 6
Most of the neutrinos here on Earth come from the Sun
Other sources, too:
Dying stars:
Supernova explosions
Relics from the Big Bang:
30 million neutrinos in each of us!
Cosmic rays hitting the atmosphere
produce neutrinos

7. 90 years ago:
A common type of radioactive decay
seemed to indicate that energy was
disappearing
From Wolfgang Pauli’s letter on 4 Dec 1930:
“Dear Radioactive Ladies and Gentlemen,
...
I have hit upon a desperate remedy to save
the [...] law of conservation of energy.”
In Pauli’s journal:
“I have done something very bad today by proposing
a particle that cannot be detected. It is something
no theorist should ever do.”
Radioactive
atom
Electron
Invisible particle

8. C. Cowan and F. Reines
Savannah River nuclear plant,
South Carolina 1956
Fred Reines and Clyde Cowan
detect neutrinos for the first time

9. Neutrinos don’t behave like the other matter particles
All the other particles that make up matter carry electric charge
(the property that allows us to make electricity)
Neutrinos have NO electric charge
Tiny mass: It weighs in at 0,0000001 of an electron
0
Neutrino

10. Neutrinos come in three different types
They can transmute in flight between the three
Neutrino oscillations

11. Messengers from the universe
Supernova SN1987a

12. Neutrino detectors

13. Man-made sources of neutrinos

14. The holy grail 1
Is the neutrino its own antiparticle?
Every particle type has an antiparticle – identical properties,
except opposite charge
n p
e-
ne
n p
e-
ne
n p
e-
n p
e-
ne
ne
XTwo-neutrino
double beta decay
Neutrinoless
double beta decay
The rarest form of radioactive decay, if observed

15. SNO+ experiment
15

16. The holy grail 2
Why is the universe full of matter
but contains almost no antimatter?
The Big Bang created matter and antimatter in equal parts
Some law of nature must treat antimatter differently than matter
This does happen – to a tiny extent with some other particles
Not enough to explain the universe we can observe
Asymmetry between neutrinos and antineutrinos?

17. The DUNE experiment
17

19. 100 trillion neutrinos
passing through each of
our bodies in here...
every second!
How many of them will collide
with an atom in your body
in your lifetime?
On average: about ONE

20. Thank you!