The invisible world The elementary particles

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# The invisible world The elementary particles - PowerPoint PPT Presentation

The invisible world The elementary particles Study Nature’s phenomena… Look for the hidden laws behind these phenomena… Experiment beyond our senses… Scale factors

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Presentation Transcript

Study Nature’s phenomena…

Look for the hidden laws behind these phenomena…

Scale factors

• Length (meters) 10-15 m = size of atom’s nucleus1 m = you4.10+16 m = distance that separate us from the star Alpha Centauri (4 light-years)
• Time (seconds) 10-23 s = lifetime of particle Z01 s = you10+17 s = sun’s lifetime
• Energies (Joules)10-19 J = energy of a photon emitted by a lamp 10-7 J = landing of a mosquito10+9 J = your meals during the day 10+16 J = atomic bomb of 1 Megaton 10+26 J = light energy from the sun…every second!

Lets enter the invisible world

10 meters

A rose tree

Lets enter the invisible world

0.1 meter = 10 cm

A fly on a rose tree leaf

Lets enter the invisible world

10-3 meter = 1 mm

The eye of a fly

Detectors of the invisible

The optical microscope

Onions cells

10 micron

Lets enter the invisible world

10-5 meter = 10 microns

A hair on the eye of a fly

Detectors of the invisible

First electronic microscope : E. Ruska and M. Knoll , 1932 (Nobel prize 1986)

The electronic microscope

• = h / p

l = longueur d’onde

h = constante de Planck

p = impulsion de la particule = mv

Chloroplast within a plant cell

Optical microscope Electronic microscope

Light beam Electrons beam

Optical lenses Electromagnetic lenses

resolution 0.5 micrometer resolution 0.0002 micrometer

0.1 micron

Lets enter the invisible world

10-7 meter = 0.1 micron

The base of the hair and cells that make the eye of the fly

A few examples of scalesThe small…

You need the same number of cells to make a human being as stars to make a galaxy (100 billions)

Lets enter the invisible world

10-8 meter ~ 100 Angströms

A DNA strand within the nucleus of a cell

Detectors of the invisible

First scanning tunneling microscope: G. Binnig et H. Rohrer in 1981 (IBM, Zürich), Nobel prize 1986

Scanning tunneling microscope (STM)

In 1990. the scanning tunneling microscope allowed researchers working at IBM to write the first letters in history written using nanotechnologies by placing 35 xenon atoms on a nickel surface.

Lets enter the invisible world

10-10 meter = 1 Angström

A carbon atom. It is one of the element that makes a molecule found in DNA

Gold atoms deposited on a layer of carbon

A few examples of scalesThe very small…

You need as many atoms to make an orange as oranges to fill the Earth

Lets enter the invisible world

10-14 meter = 10 fermis

The nucleus of a carbon atom (drawing)

A few examples of scalesThe very very small…

You need as many atom’s nucleus to fill an atom as oranges to cover France entirely…15 times!

Detectors of the invisible

Experiment ALEPH, at CERN

Lets enter the invisible world

10-15 meter = 1 fermi

A proton in the nucleus (drawing)

A proton contains 3 quarks

At the end of the invisible world

Nuclear physics and particle physics

Forces

Strong interaction

gluon

quark

quark

10-14 m

Forces

Electromagnetic interaction

photon

electron

quark

Billions of km

Forces

Weak interaction

W+

neutrino

quark

10-14 m

n → p + e- + ne

W+ W- Z0

Unification of the interactions

Unification of the 3 interactions: electromagnetic, weak and strong

Weak interaction + electromagnetic interaction = electroweak interaction

(1967-1973) Glashow, Salam, Weinberg

Need Higgs

102 105 1010 1015

GeV

1 GeV = 1.6 1010 Joules

Forces

Gravitation interaction

graviton

electron

quark

Billions of km

Lets summarize:Matter and forces…

http://www.diffusion.ens.fr/vip/tableG00.html

…and the anti-matter

1928 : P. Dirac predicts the existence of anti-matter

Anti-electron trace in a C. Anderson bubble chamber

1932: C. Anderson discovers the anti-electron

Collision between a electron and an anti-electron 1993: the LEP at CERN

…anti-matter (2)

C(A) C(B)

CP(A) CP(B)

A B

Three fundamental transformations:

P: parity inversion

C: matter  anti-matter

T: time reversal

A B CPT(A) CPT(B)

http://ppd.fnal.gov/experiments/e871/public/phys_slides.html

…anti-matter (4)

• Symmetry violated: P parity
• Are there any other symmetries violated? Symmetry C matter ↔ anti-matter ?

Left

Right

Left

Left

?

Right

Right

…anti-matter (5)

Cosmic microwave background has been measured

Today in our universe

This ratio was though to be in the past

• Diffuse cosmic background
• First nucleosynthesis models
• Number of stars

At the beginning, for 1 billion anti-matter particles,there must have been 1 billion and 3 matter particles

One condition:CP violation

…anti-matter (6)

The search for cosmic anti-matter

To observe anti-matter in space, we « only » need sending a magnet

Cosmic ray

matter

Anti-matter

we can count cosmic rays and classify them by types

The experiment AMS (Alpha Magnetic Spectrometer) was conceived to observe anti-matter in space

…Anti-matter (7)

A simple magnet is not enough, we also need a particle physics detector

• AMS 02
• Space constraints
• Mass < 7 t
• 3 m x 3 m
• Power consumption < 2 kW
• Resistance :
• Temperature -50° / +50°
• Vacuum
• Vibrations
• ATLAS for the LHC
• More than 7000 t
• 44 m x 20 m
• Power consumption > MW
• Immobilised 100m under ground

…anti-matter (8)

Particle identification in AMS

The detectors need to be very precise. We need to be able to reject:

1 proton in 104 positons

1 Helium in 103 positons

1 électron in 102 positons

1 proton in 106 photons

Experiments that changed everything

E. Rutherford, H. Geiger et E. Marsdensent Helium particles (alpha particles) on gold leaf/sheet.

Surprise: the gold leaf/sheet looks like butter containing very small particles. Rutherford will interpret these as Gold atom’s nuclei

ne

00ne

W. Pauli suggests a new particle: the neutrino

Experiments that changed everything

The mystery of beta disintegration

Experiments that changed everything

1 neutrino out 1020 interacts with the detector !

Reactor: 1020 neutrinos/sDetector at 12m3 neutrinos detected every hour

The first neutrino detector.

Built in 1956 by C. Cowan et F. Reines,near Savannah River’s nuclear reactor, USA

Experiments that changed everything

1968

1974

1977

1983

1993

1995

SLAC: discovery of quarks

Electrons-protons collisions

SLAC and Brookhaven: discovery of quark « charme »electrons-positrons collisions

Fermilab: discovery of quark « bottom »protons-protons collisions

CERN: discovery of bosons W and Z

protons-antiprotons collisions

CERN: only three family of particles

electrons-positrons collisions

Fermilab: discovery of quark « top »proton-antiproton collisions

Today’s experiments

Giant detectors for tiny particles…

SuperKamiokande track the sun’s neutrinos

ALEPH detector studied high energy collisions

The theory that changed everything…quantum mechanics

Some of the players

E. Fermidescribed weak interaction

W. Paulipredicted the existence of the neutrino

L. De Brogliepredicted wave-particle duality

P. Diracpredicted the existence of anti-matter

Quantum mechanicsa new way to see the invisible

Particle and wave  wave function: y

Ey = Hy

Distribution of the probability of finding an electron in an atom

Orbitale 2s

Orbitale 2p

Orbitale 3d z

http://hypo.ge.ch/physic/simulations/orbitales/orbitales.html

« Old » way to look at electrons in an atom

The mystery of quantum mechanics

Thomas Young’s experiment with photons

The mystery of quantum mechanics

Thomas Young’s experiment with electrons

Seeking to understand what matter is made out of…Trying to see the invisible…

…has led to a better understanding of the human body, our Sun inner workings, the development of new materials (semi-conductors) or new light sources (such as lasers)