frank linde nikhef & uva +31-205925001 f.linde@nikhef.nl

Frank LindeNikhef & UvA

+31-205925001f.linde@nikhef.nl

MicrocosmosI. The Wild World of Subatomic ParticlesII. The Story of the HiggsIII. The Mystery of Dark MatterIV. Particle Physics and You!

Elementary Particle Physics

Dark

ag

es

Long ago …Empedocles Plato

Aristoteles

Leucippus

Democritus

AirWaterFireEarth

Atoms

Lead

Gold

Alchemy

01

00

20

03

00

40

05

00

60

07

00

80

09

00

100

01

10

01

20

01

30

01

40

01

50

01

60

01

70

01

80

01

90

02

00

0

Wate

r ele

ctro

lysi

s

Atoms NA = 6.0221420 1023/Mol

Number of atoms per volume independent of atom type!(Avogadro)

22.4 liters NA atoms

=1 Mole

How large? 30-3001012 meters

How heavy? 2-4501025 kilograms

How many? 31023/gram hydrogen

gas

nummering: kernlading

Het Periodiek Systeem

Periodic Table of Elements

Nobel gasses

Not part of the original Mendeleev

periodic table

Th

e a

tom

Thomson1897

Thomson1897

e/m = 1.761011 C/kg

Millikan1900

qe = 1.60217646 1019 Cme = 9.1093819 1031 kg

electron

Atoms: Rutherford’s view

Elementary particles (1932):Electron, Proton & Neutron

1897electronThomson

1911nucleusRutherford

1911protonRutherford

1932neutronChadwick

Physics just before 1900

??????? all ok ???????No: few “minor” problems:

· “black body” radiation· no eather?· natural radioactivity (Curie et al.)

· stability of the Rutherford atom

Don

e?

I.Special relativity

1905

Intermezzo: Einstein & relativity

Time travel becomes a reality!

L

t = 2Lc

observer at rest

‘hence-and-forward’light flash period t:

‘click’ of the light clock at rest: t

c=299792458 m/s (exact)

Moving clock ‘clicks’ slower!

‘click’ of the moving light clock: t’

v [m/s]

½vt’

L

vt’

t’ = 2L2+(½vt’)2

c (ct’)2 = 4L2+(vt’)2

t’ = = 2Lc2v2

t1v2/c2

observer moving with velocity v

‘hence-and-forward’light flash period: t’

c=299792458 m/s (exact)

t

II.Quantum world

1900-19

Imag

inati

on

Planck (1858-1947)

Planck1900

Einstein (1879-1955)

Einstein1905

Compton (1892-1962)

Compton1922

Light: quantum effects

I. Black body radiation

Planck 1900

L

Easier to fit short wavelengths!

=½L=1L=2L

Stacking waves!

Fit ½, 1, 1½, 2, etc. wavelengths in box such that amplitude=0 on

walls

Light wave's energy: classical

|amplitude|2

energ

y

E continuous!

Radiated energy spectrum: classical

wavelength ()0 m 0,5 m

en

erg

y d

en

sity

kT1λ

8πλρ4E

ult

ra-v

iole

t ca

tast

roph

Light wave's energy: quantum

E = hf

E = 2hf

E = 4hf

E = 3hf

E = 5hf

energ

y

# quanta N

E discrete!

E = Nhf Planck’s constant h = 6.62606881034 J/s

wavelength ()0 m 0,5 m

en

erg

y d

en

sity

λhc

1e

1

λ

8πλρ λkThc4E

Radiated energy spectrum: quantum

ult

ra-v

iole

t ca

tast

roph

Color

T=15,000 oC

T=12,500 oC

T=10,000 oC

T=7,500 oC

T=2,500 oC

T=5,000 oCthe sun

Universe as black body radiator

T 2.725 K 270.5 oC

Big Bang’s afterglow on your TV

incident lightwavelength (frequency f)

slab of materialEinstein 1905

II. Photo electric effect

knocked outelectrons

Compton 1922

III. Compton effect

incident lightwavelength scattered

electron

scattered lightwavelength ’

Duality: wave & particle characteristics

It is safe to say that nobody understands quantum mechanics. R.P. Feynman

Quantum mechanics is magic.Daniel Greenberger.

Everything we call real is made of things that cannot be regarded as real. Niels Bohr. Those who are not shocked when they first come across quantum theory cannot possibly have understood it. Niels Bohr.

If you are not confused by quantum mechanics, you do not understand it. John Wheeler.

If quantum theory is correct, it signifies the end of physics as a science. Albert Einstein.

I do not like quantum mechanics; I am sorry I ever had anything to do with it. Erwin Schrödinger.

morequotes

Atom: quantum effects

Bohr1910

Bohr (1885-1962)

Schrödinger1927

Schrödinger (1887-1961)

Heisenberg1925

Heisenberg (1901-1976)

Bohr’s atom model

1234n = 5

n=3

n=2n=1

Balmer serie

eVn

13.6E 2n

μm10.97n

1

2

1 122

μm10.97n

1

3

1 122

μm10.97n

1

1

1 122

1

2

3

13.6

3.4

1.5

0.0

Balmer

bin

din

g e

nerg

y (

eV

)

quan

tum

num

ber

(n)

Paschen

LymaneV

n

13.6E 2n

eV

f [1/s]

f large

t small

t [s]

f [1/s]

f small

t large

t [s]

Heisenberg’s uncertainty principle

electron

light

micr

osco

pe

electron

light

micr

osco

pe

4/2

Schrödinger’s wave equation

n=1

1H ground state

n=1

n=2

n=3

“s” states

“p” & “d” states

Electron: quantum details

Uhlenbeck & Goudsmit1925

(1887-1961) (1901-1976)

Lorentz & Zeeman1896

(1885-1962) (1887-1961)

Leiden Leiden LeidenAmsterdam

(1900-1958)

Pauli1925

N

Z

N

Z

Zeeman

SternGerlach

Electron spin!

UhlenbeckGoudsmit

Democracy: all electrons are equal

Pauli:

Each electron in a different state! electron =

asocial

The electronMass:0.000000000000000000000000000910938188 gram

Mean lifetime: (infinite) seconds

Electric charge:0.00000000000000000016021765 Coulomb

”Spin”: ½

Perfect description of atoms!

‘Physics 2000’website(Colorado)

Relativistic quantum theory

Dirac1928

Dirac (1902-1984)

Feynman1947

Feynman (1918-1988)

Anderson1932

Anderson (1905-1991)

Dirac’s anti-matter hypothesis

e+

e

e+e

e

e+

neg

ati

ve e

nerg

yp

osi

tive e

nerg

y

Anderson’s anti-electron discovery

e+e

Positron EmissionTomograph

Angels & Demons: the movie

creation & annihilition

time

the only interaction

Bhabha scattering:

Pair creation:

Pair annihilation:

Compton scattering:e e

Möller scattering:ee ee

e+e e+e

e+e

e+e

Real fun:

Part

icle

colli

sion

s

boringcollisions

excitingcollisions

E=mc2funcollisions

highenergy

largemass

E=mc2

Frank LindeNikhef & UvA

+31-205925001f.linde@nikhef.nl

MicrocosmosI. The Wild World of Subatomic ParticlesII. The Story of the HiggsIII. The Mystery of Dark MatterIV. Particle Physics and You!

Elementary Particle Physics