Nuclear and
Particle Physics
An Introduction
Spring 2014 13.01-­‐26.05 Monday 1415-­‐1600, Aud. Ø467 Thursday 1015-­‐1200, Aud. Ø467 Web site 2014 Additional material Farid Ould-­‐Saada ¡
Web site §  Course content & goals §  Practical: teaching, lectures vs exercises, evaluation ¡
2014 §  Time, pensum, other recommended material ¡
Additional material §  Material from last year (kept) and is being updated §  Note colour coding: ▪  Red=important information; Yellow=working on it; Green=ready for “printing” ¡
¡
CERN visit 2013 International Master Classes -­‐  Modern Particle Physics, 2013, Thomson -­‐  Particles and Fundamental interactions, 2012, Braibant et al -­‐  Introduction to Nuclear and particle physics, A. Das, T.Ferbel -­‐  CERN summer student lectures -­‐  Review of particle properties -­‐  Nobel Lectures in Physics -­‐  HyperPhysics
¡
Exercise sessions §  “Pensum” book has sets of problems with “solutions” §  Solve as many as you can §  Exercise sessions will be organised when needed ¡
Compulsory “projects” and final exam §  3 compulsory “projects” and final oral exam ¡
Nuclear physics course – in parallel with FYS3510 §  FYS3520 – Nuclear physics, structure and spectroscopy ¡
Some related (future) courses: §  FYS4170 – Relativistic Quantum Field Theory §  FYS4550 – Experimental High Energy Physics §  FYS4560 – Elementary Particle Physics §  FYS4530 – Subatomic many-­‐body theory ¡
About yourselves §  Following Nuclear Physics Course (FYS3520)? §  Quantum mechanics introduction? §  Special relativity introduction? Including 4-­‐vectors, … ? §  Master classes? Heard of? Participated? §  Visited CERN? ¡
About myself §  Farid Ould-­‐Saada or Farid Ould-­‐Saada ¡
Feedback most welcome ¡  Feedback is needed in order to plan some trip ~March, April or May §  Short discussion §  Institute contributes with 15 kNOK (in total) … ▪  So some “own contribution” is expected ¡  CERN Student program §  http://jobs.web.cern.ch/join-­‐us/students §  Summer student Deadline 31.1.2014 §  Technical student Deadline 6.5.2014 ¡
1. Basic Concepts §  Appendix B – Special relativity ¡
¡
3. Particle Phenomenology 2. Nuclear Phenomenology §  Appendix A – Quantum Mechanics , Appendix C – Rutherford scattering ¡
¡
¡
¡
¡
¡
4. Experimental Methods – (shorter version) 5. Quark Dynamics: The Strong Interaction 6. Weak Interactions And Electroweak Unification 7. Models And Theories Of Nuclear Physics 8. Applications Of Nuclear Physics (only selected topics) 9. Outstanding Questions and Future Prospects 25/01/14
F. Ould-Saada
6
1 History and current research ¡  The origin of Nuclear Physics ¡  The emergence of particle physics ¡  The Standard Model and Hadrons ¡  CERN LHC Highlights 2 Relativity and Antiparticles. 3 Space-­‐Time Symmetries and Conservation Laws. Parity
Charge Conjugation
Time Reversal 4 Interactions and Feynman Diagrams. 5 Particle Exchange: Forces and Potentials. Range of forces, The Yukawa potential 6 Observable Quantities Amplitudes, Cross-­‐sections, Decay rates of unstable particles 7 Units: Length, Mass and Energy. 25/01/14
F. Ould-Saada
7
¡
Origins of Nuclear Physics (NP) ¡
NP distinct from Atomic Physics §  1896 -­‐ Becquerel: some nuclei unstable and decay spontaneously §  Radioactivity: α (4He++), β (e-­‐, e+), γ (photons) ¡
J.J. Thomson – 1897: cathode rays are electrons e-­‐ §  Nature of atoms: “plum pudding model” with + and – charges ▪  Addresses stability of atoms ▪  but no account of discrete wavelengths in emitted spectra of light ¡
Rutherford 1911: large angle scattering of particles by thin gold foils §  very small, electrically charged central nucleus §  “planetary atom model” with e-­‐’s on discrete orbits around nucleus §  explains discrete light emission in decay of excited atoms ▪  Hydrogen = proton + electron 25/01/14
F. Ould-Saada
8
§
Planetary atom ▪  Masses of natural elements are integer multiples of a unit 1% smaller than mH ▪  mC=12.0 ; mN=14.0 in such units ▪  But not all atoms obey rule! Chlorine=35.5 ▪  Soddy – Isotopes : §
▪  atoms whose nuclei have different masses but same “charge” ▪  Natural elements are mixtures of different isotopes à observed masses Chadwick – 1932: neutron, n, neutral radiation emitted in α-­‐Be ▪  Final ingredients for understanding nuclei? §
Bohr – 1913: “Bohr model” using Quantum Mechanics (QM) ▪  Avoids atom collapse in planetary version based on classical mechanics ▪  Phenomena of atomic physics explained by Dirac equation – relativistic analogue of Schrödinger equation ▪  Heisenberg et al.: application of QM to Nucleus made of nucleons (p,n) ▪  Force binding nucleus is not electromagnetism holding electrons in their orbits, but a short-­‐range, charge-­‐independent, Strong Nuclear force §
Different models are used to interpret various classes of phenomena in Nuclear Physics 25/01/14
F. Ould-Saada
9
Early 1930s: elementary particles ¡
¡
¡
Electron e-­‐-­‐ (Thomson 1897), proton p (Rutherford 1919), neutron n (Chadwick 1932) Photon γ §  Planck 1900: quantization of EM radiation to explain black-­‐body radiation Neutrino ν §  Pauli 1930: postulated neutral spin1/2 particle to explain apparent non-­‐
§
conservation of energy and angular momentum in b-­‐decays, 3-­‐body instead of 2-­‐body decay to e-­‐+p) §  Reines-­‐Cohen-­‐ 1956: detection of antineutrino at nuclear reactor 1950s: High energy beams of particles in laboratories ▪  Controlled scattering experiments, greater use of computers, sophisticated §
analysis techniques 1960s: large number of unstable particles with very short lifetimes à “Particle Zoo” ▪  Quark model: Gell-­‐Mann & Zweig à 3 families of more fundamental particles – Quarks, q confirmed in deep inelastic scattering eN and νN 25/01/14
F. Ould-Saada
10
Model
predicts
particles like
the Ω Particle!
From
Hadrons
to
quarks
•  All hadrons are made of a smaller number of yet more fundamental particles, quarks •  As confirmed by experiments by shooting high energy electrons on nucleons (p,n) •  Protons and Neutrons are made of quarks bound by gluons. ¡
¡
Explains nearly all particle physics phenomena, except Gravity Interaction of a small number of elementary (fundamental) particles §  Single theory to interpret all HE data, contrary to nuclear physics ¡
Elementary particle characterized by quantum numbers: mass m, electric charge q, spin s=0,1/2,1,3/2, … §  Spin : permanent angular momentum in QM – no classical analogue §  Fermions: half-­‐integer spin (electron: s=1/2) §  Bosons: integer spin (photon: s=1, Higgs: s=0, “Graviton”: s=2) ¡
3 families of particles in SM §  2 spin-­‐1/2 families of fermions: Leptons (electron, neutrino) and Quarks (u,d) §  1 family of spin-­‐1 bosons §  (at least) one spin-­‐0 Higgs boson to explain origin of mass A (scalar) Higgs boson discovered by ATLAS&CMS @ CERN
25/01/14
F. Ould-Saada
14
•
1st generation:
–  All ordinary matter belongs to this group
–  Neutrinos needed in most matter transformations
•
2nd and 3rd generations:
–  Existed just after the Big-Bang
–  Now found only in Cosmic rays or produced at high
energy Accelerators
•
Each particle
also has an
antimatter
counterpart ...
sort of mirror
image.
The 4
fundamental
forces of
nature are
carried by
Bosons:
- 8 Gluons
- 1 Photon
- 3 W+, W-, Z0
- 1 Graviton?
¡
Electromagnetic §  All electrically charged particles: electron, quarks, W-­‐bosons §  Massless γ à long range interaction ¡
Weak §  all particles (but gluons and photons), including neutrinos and Higgs §  Heavy W+,W-­‐, Z0 m=80-­‐90 GeV à short range interaction ¡
Strong interaction §  Only quarks (and gluons) bound in nucleons §  Massless gauge bosons but short range due to confinement §  Strong nuclear forces (in NP) are a consequence of this more fundamental strong interaction 25/01/14
F. Ould-Saada
17
¡
Free quarks unobserved in nature §  Hadrons made of quarks §  Quark properties deduced from studies of hadron properties ¡
Analogy to deducing properties of nucleons by studying nuclei … §  Nuclei are bound states of nucleons … §  Nucleons are bound states of quarks §  Are properties of Nuclei deducible from properties of quarks and their interaction, i.e. the SM? ¡
In practice, it is beyond present calculation techniques §  NP and PP treated as 2 almost separate subjects §  However there are many connections between the fields 25/01/14
F. Ould-Saada
18
q  Quarks are not free, they come in 3 colors and are
confined in Hadrons
q  Only colorless combinations of quarks exist in nature
Ø  Mesons = quark-antiquark (π+, π0, π- )
Ø  Baryons = qqq (p,n)
The four fundamental forces are
carried by vector field particles bosons
If you change the strength of any
interaction, you would arrive to a
totally different world …
Is the
relative
strength
always
Like that?
- No, it
depends
where you
live!
?
Just
after the Big-Bang
it is believed that all 4 forces had the same strength …
25/01/14
F. Ould-Saada
20
Our current
understanding
leads to a
coherent
picture of the
Universe:
Astronomy:
Statistics:
v=Hd
E=kT
Relativity:
Quantum mechanics
E=hν=hc/λ
…and a series of
phase transitions
¡  Student contacts ¡  Course evaluation §  Mid-­‐term evaluation ▪  You will have the chance to give feedback in order for me to improve the teaching “on the fly” §  Final evaluation ▪  Student contact collects input from students ▪  Meeting ▪  Report ¡
(N2) gas (10-­‐8cm) in a room at NTP (293oK, 1 Atm) ¡
M=28 . 1,66 . 10-­‐27 kg ; k=1,38 . 10-­‐23 J K-­‐1 ; 1eV=1,602 . 10-­‐19 J 1
2
m〈v 2 〉 = 23 kT ≈ 0.038 eV
2
⇒ 〈v 〉 = 510m s
−1
Ek ≅ 1, 3⋅10 −4 T [ K ]
t [ s ] ≅ 2, 25⋅10 20 T −2 $%K −2 &'
From S. Braibant et al.; Particles and fundamental interactions
¡
¡
¡
Very hot
Very Cold
¡
¡
¡
Travel back in time TeV scale !1ps ¡  – 13.7 M years starting totally symmetric with Big Bang some 13.7M years ago cooling towards current 2.7º K while expanding, went through successive phase transitions with associated Symmetry Breakings, led to a diversity of fields responsible for 4 ``fundamental'' forces PV=nRT
25/01/14
F. Ould-Saada: LHC - Fysikk
? 25
Towards higher symmetries …
High Symmetry
“Chaos”
High Energy Physics
A simple, single
theory
Experiment not accessible
Astronomy
Chemistry
Biology...
Various theories describing
Various aspects of Nature
SM describes Nature up to ~1 TeV
Towards unification of all fundamental forces …
Current
experimental limits
?
¡
The Standard Theory of Particles and Forces ¡
All forces in nature obey a form of symmetry.
§  Gauge-symmetry
¡
The Standard Model (SM) describes interactions
between elementary particles grouped in 3
families of quarks and leptons
¡
The Standard Model
§  unifies Electromagnetism (long range, macroscopic,
H?
photon has no mass) and Weak force (short range,
microscopic, W and Z are heavy) …at high energies
§  describes (almost) all current particle physics data
¡
¡
The Electroweak symmetry
must be broken at low
energies in order to give the
weak bosons (W,Z), as well as
all matter particles, masses.
A scalar field requiring a new
particle, the Higgs Boson ...
¡
What is the origin of mass?
§  Newton: Weight proportional to mass
§  Einstein: Energy related to mass
§  ... neither explained origin of fundamental particle masses ...
¡
Although most of mass of ordinary matter (p,n) is due to
kinetic energy of its constituents (quarks)
§  what gives mass to quarks and electron?
§  Massless electrons would be flying around at speed of light
and there would be no matter …
¡
Is mass due to the Higgs boson (through its field), the only
missing particle of the Standard Model?
¡
Whole Universe swims in an invisible, cosmic field, Higgs-field, which acts on
particles and provide them with what is called mass.
All fields have associated boson. The Higgs-field has its Higgs-boson.
¡
§  Forces are dictated by (gauge) symmetries ú
Fermions in 3! = SU(3)C*[SU(2)L*U(1)Y] à QCD + Electroweak (“=“ QED + Weak) §  Symmetries of laws do not necessarily lead to symmetries of outcomes Electroweak symmetry spontaneously broken – Brout Englert Higgs mechanism ú  BEH “hides” EW symmetry, gives masses to weak gauge bosons and “approves” fermion masses, predicts couplings of particles to Higgs, and more ú
§  Higgs boson mass is not predicted by the SM §  è Must be measured Higgs and more -­‐ F. Ould-­‐Saada 25/01/14 32 q  Particle collisions at LHC Ø  Simulated proton + proton à black hole candidate Ø  LHC collides also heavy ions: pb-­‐pb and p-­‐pb q  Sensitivity to rare phenomena – with small cross sections – depends on the luminosity Higgs and more -­‐ F. Ould-­‐Saada 25/01/14 33 Number of collisions N = L . σ (pp → X) n. of protons
per bunch
Luminosity L
n. of bunches
N 2k b f
L=
4πσ xσ y
n. of turns
per second
beam size at IP
(σx,y = 16 µm)
€
Cross-section
σ
Very small
for new
processes
25/01/14 F. Ould-­‐Saada: HEPP & ATLAS 34 45 m
ATLAS superimposed to
the 5 floors of building 40
24 m
7000 Tons
35
Let’s build ATLAS in ~ 1 minute … Higgs and more -­‐ F. Ould-­‐Saada 25/01/14 36 A real event in a detector … Higgs and more -­‐ F. Ould-­‐Saada 25/01/14 37 Particle detection "   the various
particles have
different signatures
in different parts of
the detector
"   by combining the
various signatures,
we can reconstruct
how the particle
moved through the
detector
25/01/14
F. Ould-Saada: HEPP & ATLAS
38
Particle identification Higgs and more -­‐ F. Ould-­‐Saada 25/01/14 39 HàZZ*àµ+µ-­‐µ+µ-­‐ Higgs and more -­‐ F. Ould-­‐Saada m4=127.4 GeV. m12=86.6 GeV, m34=31.6 GeV 25/01/14 40 Hàγγ Higgs and more -­‐ F. Ould-­‐Saada 25/01/14 41 Hàγγ Higgs and more -­‐ F. Ould-­‐Saada 25/01/14 42 Anything new? Invariant mass of photons Higgs particle at 126 GeV! 43 §  What about the strong interaction – QCD? ú  Especially at high energies and densities ú  Asymptotic freedom vs confinement §  p-­‐p vs pb-­‐pb vs p-­‐pb collisions ú  ALICE, ATLAS and CMS à observation of jet-­‐quenching §  Sign of quark-­‐gluon plasma? ú  Another phase transition Experimental Particle Physics @ UiO
F. Ould-Saada, 11/2012
44
ALICE §  Mission ú  High Energy Heavy Ion collisions ú  Comparison of pb
+pb , p+p and p
+pb collisions ú  Investigating the Quark Gluon Plasm (QGP), predicted by QCD, in the LHC energy regime. F. Ould-Saada, 11/2012
45
Pb
Pb
Heavy ion collisions p
π-
π+
Water phase transition solid
liquid
vapor
Temperature
Tc
Early universe
QCD phase transition diagram quark-gluon plasma
hadron gas
nucleon gas
nuclei
ρ0
net baryon density
F. Ould-Saada, 11/2012
48
QCD phase transition diagram Studying the phase transitions of quark-gluon plasma allows us to understand the
behavior of matter in the early universe, just fractions of a second after the Big Bang, as
well as conditions that might exist inside neutron stars. The fact that these two disparate
phenomena are related demonstrates just how deeply the cosmic and quantum worlds are
intertwined. Credit: Brookhaven National Laboratory
¡
High Energy Physics may provide answers
to some outstanding problems in
Astrophysics and Cosmology
§  What is the origin of mass? BEH mechanism!
§  What is dark matter? What is dark energy?
§  Do extra dimensions exist?
§  What is the Universe’s original symmetry?
§  What happened with the original symmetry?
§  What happened with the original antimatter?
§  How did Universe evolve?
Vacuum with scalar field (`Higgs’)
Spontaneous symmetry breaking
Quark-gluon plasma
Supersymmetric particles
Extra dimensions, graviton
¡
CERN §  The place where things happen … 25/01/14
F. Ould-Saada
51
CERN
A research
laboratory
for thepour
worldla Recherche
Conseil
Européen
- ~10000 scientists from more than 110 countries
Nucléaire
Situated between Geneva and France
Fundamental research in particle physics
- seeking answers to questions about the Universe
What is it made of?
How did it come to be the way it is?
Advancing the frontiers of technology and engineering
- Medicine,
- IT (WWW, Grid)
Training the young scientists and engineers …
- the experts of tomorrow
World’s
leading
Norway
is one of
CERN’s research
20 members centre
in particle physics
4 large experiments at LHC to explore a new energy era CMS: 2900 physicists
184 Institutions
38 countries
Multipurpose
LHCB 700 physicists
52 Institutions
15 countries
matter-antimatter
ALICE; 1000 physicists
105 Institutions
30 countries
q-g plasma
and 3 smaller experiments
TOTEM
LHCf
MoEDAL
Korea and CERN / July 2009 53 ATLAS : 3030 Physicists
174 Institutions
38 countries
Multipurpose
¡  Feedback is needed in order to plan some trip ~April 7-­‐10 §  Must start planning very soon §  Institute contributes with 15 kNOK (in total) … ▪  So some “own contribution” is expected ¡  CERN Student program §  http://jobs.web.cern.ch/join-­‐us/students §  Summer student Deadline 31.1.2014 §  Technical student Deadline 6.5.2014