1 PHL424: Nuclear and Particle PhysicsLectures: Hans-Jürgen Wollersheim office: phone: Monday :00 – 9:50 Tuesday :00 – 9:50 Wednesday :30 – 2:20 Thursday(T) :30 – 2:20

2 Tentative outline of Nuclear PhysicsGross properties of nuclei Rutherford scattering nuclear radii, masses, and binding energies Bethe-Weizäcker mass formula angular momentum, magnetic moment Radioactivity α - decay β - decay γ – decay Fundamental forces nuclear force between nucleons nuclear shell model spherical and deformed nuclei Nuclear reactions direct reactions fusion reaction

3 Literature Recommended Textbook Supplemental Textbook

4 neutron star unstable nuclei supernovae sun heavy ion nuclear reactions

5 Brief historical overview in search of the building blocks of the universe ...Greek philosophers 4 building blocks earth air 5th BC - Democritus atomic hypothesis water fire 18th – 19th century Lavoisier, Dalton, ... put atomic hypothesis on firm basis distinction between compounds and pure elements 1896 Dmitri Mendeleev 92 building blocks (chemical elements) 1H, 2He, U

6 Brief historical overview in search of the building blocks of the universe ...1896 Henri Becquerel discovers radioactivity electromagnetic wave Helium nucleus electron emission of radiation from atoms 3 types observed: α, β and γ α and β deflected in opposite direction opposite charges α deflected less than β α must have larger mass γ not deflected uncharged ~1900 Ernest Rutherford investigates new radiation “... it was as incredible as if you had fired a 15-inch shell at a piece of tissue paper and it came back and hit you” α and β emissions change nature of element α‘s charge = +2e α‘s mass ~ 4H β radiation = electrons γ = electromagnetic radiation (photons) expected α’s (2He) pushed a little to the side by charges of atom (79Au) observed some α’s deflected backwards to 1800!! 1911 Ernest Rutherford tests Thomson’s model of the atom N electrons (-e·N) embedded in (+e·N) charge uniformly distributed over atomic volume “plum pudding model”

7 Brief historical overview in search of the building blocks of the universe1913 Niels Bohr planetary model of atom all positive charges (and ~ all mass) concentrated in tiny region at the center 1920 Francis William Aston mass spectrograph measures masses of atoms mass charge He ~ 4 H He = 2 H C ~ 12 H C = 6 H O ~ 16 H O = 8 H 𝐸 𝐵 1925 Werner Heisenberg quantum mechanic simplest atom = H its nucleus = proton hypothesis of neutral particle in nucleus with m ~ mp 1932 James Chadwick discovers the neutron 3 building blocks electron + proton + neutron NUCLEAR PHYSICS

8 Brief historical overview in search of the building blocks of the universe1932 Enrico Fermi developed the theory of β-decay 1934 Irene Joliot-Curie & Frederic Joliot artificial radioactivity 13 27 𝐴𝑙 𝐻𝑒 → 𝑃 ∗ +1𝑛 1934 Hans Bethe liquid drop model and mass formula 1938 Otto Hahn, Lise Meitner & Fritz Strassmann discover nuclear fission 1948 Maria Goeppert-Mayer & J. Hans D. Jensen develop the nuclear shell model

9 Brief historical overview in search of the building blocks of the universe1953 Aage Niels Bohr, Ben Roy Mottelson, Leo James Rainwater developed the collective nuclear model 1956 Frederick Reines & Clyde L. Cowan discovery of the neutrino 1983 Carlo Rubbia discovery of the W and Z Boson 1998 Takaaki Kajita & Arthur B. McDonald discovery of neutrino oscillations neutrinos must have some mass

10 The Nobel Prizes in Physics (Chemistry) in the 20 and 21 centuries1903: Radioactivity (Henri Becquerel, Marie & Pierre Curie) 1906: Discovery of electron (J. J. Thompson) 1908: Disintegration of the elements (Ernest Rutherford) 1922: Structure of atoms (Niels Bohr) 1929: Wave nature of electrons (Prince Louis-Victor Pierre Raymond de Broglie) 1935: Discovery of neutron (James Chadwick) 1936: Discovery of positron (Carl David Anderson) 1938: New radioactive elements produced by neutron irradiation (Enrico Fermi) 1939: Cyclotron (Ernest O. Lawrence) 1949: Theoretical work on nuclear forces (Hideki Yukawa) 1951: Transmutation of atomic nuclei (John Douglas Cockcroft & Ernest Thomas Sinton Walton) 1952: Nuclear Magnetic Resonance (Felix Bloch & Edward Mills Purcell) 1957: Parity violation (Chen Ning Yang & Tsung-Dao Lee) 1959: Discovery of antiproton (Emilio Gino Segre & Owen Chamberlain) 1961: Electron scattering and resonance absorption (Robert Hofstadter & Rudolf Ludwig Mössbauer) 1963: Nuclear shell model (Maria Goeppert-Mayer & J. Hans D. Jensen) 1967: Nuclear reactions and energy production in stars (Hans Albrecht Bethe) 1969: Quarks (Murray Gell-Mann) 1975: Collective and particle motion (Aage Niels Bohr, Ben Roy Mottelson & Leo James Rainwater) 1984: Discovery of W and Z bosons (Carlo Rubia & Simon van der Meer) 1989: Development of ion trap technique (Hans G. Dehmelt & Wolfgang Paul) 1992: Multi Wire Proportional Chamber (Georges Charpak) 1995: Discovery of tau and detection of neutrino (Martin L. Perl & Frederick Reines) 2008: CKM matrix element (Makoto Kobayashi & Toshihide Masukawa) 2013: Theoretical work on origin of mass of subatomic particles (Francois Englert & Peter W. Higgs) 2015: Discovery of neutrino oscillations (Takaaki Kajita & Arthur B. McDonald) Henri Becquerel Nobel price 1903 Marie Curie ( ) Piere Curie ( ) Nobel price 1903

11 Discovery timeline 1896: Henri Becquerel discovers radioactivity in Uranium salt 1898: Marie & Pierre Curie discover Polonium and Radium (new elements) 1907: Ernest Rutherford classified α-, β-, γ-radiation (α ≡ 4He nucleus) 1911: Rutherford, Geiger and Marsden discovered the atomic nucleus 1913: Bohr model of the hydrogen atom 1919: first nuclear reaction by Rutherford 14N + α → 17O + p 1930: Ernest O. Lawrence invented the cyclotron 1932: Enrico Fermi developed the theory of β-decay 1935: Hideki Yukawa postulates the theory of strong interaction (pion) Bethe-Weizäcker mass formula & liquid drop model 1938: Hans Bethe postulates CNO fusion reaction for stellar energy 1939: O. Hahn, F. Straßmann and L. Meitner discover nuclear fission 1946: F. Bloch and E. Purcell improve NMR technique 1949: M. Goeppert-Mayer proposed the nuclear shell model 1957: beginning of nuclear astrophysics (Burbidge2, Fowler, Hoyle-article to nucleosynthesis) 1967: J. Bell and A. Hewish discover pulsars (neutron stars) 1986: first observation of double-β decay 2νββ (rarest decay) 2006: production of the so far heaviest element (element Z = 118) Henri Becquerel Nobel price 1903 Marie Curie ( ) Piere Curie ( ) Nobel price 1903

12 So ... Where Do We Start? Scales in the UniverseWe need a point of reference to start discussing nuclear physics. crystal molecule atom nucleus proton quark

13 Nuclear units and physical constantslength unit: Fermi = femtometer = fm = [m] energy unit: MeV = 106 eV = 106·1.602·10-19 CV = 1.602·10-13 [J] mass unit: 1 u = 1/12·m[12C] = MeV/c2 = ·10-27 [kg] time unit: [s] or [fm/c] ≈ 3·10-24 [s] Albert Einstein Nobel price 1921 𝐸=𝑚∙ 𝑐 2 Constant of nature relevant to nuclear physics speed of light in vacuum, c = ·108 [m/s] Planck’s constant / 2π = ħ = ·10-22 [MeV s] = 1.054·10-34 [J s] ħc = [MeV fm] fine structure constant (dimensionless), α = e2/(ħc) = 1/ → e2 = α·ħc = [MeV fm] elementary charge, e = 1.602·10-19 [C] or e = 𝑀𝑒𝑉 𝑓𝑚 rest energy of proton, mpc2 = [MeV] rest energy of neutron, mnc2 = [MeV] rest energy of electron, mec2 = [MeV] Avogadro’s number, NA = ·1023 /mol E – p relationship: Kinetic energy: 𝐸 2 = 𝑝 2 𝑐 2 + 𝑚 𝑐 4 𝑇=𝐸− 𝑚 0 𝑐 2 = 𝑚 0 𝑐 2 𝛾−1

14 between electronic statesThe atom atomic excitations ~ eV caused by transitions between electronic states atom is a neutral system ~ m

15 Bohr atomic model absorption spectrumHydrogen gas Hydrogen absorption spectrum

16 Bohr atomic model emission spectrumHelium emission spectrum

17 between nuclear statesThe atomic nucleus nuclear excitations ~ eV caused by transitions between nuclear states proton (π) + neutron (ν) ~ m = fm excitations can be caused by individual nucleons or as a collective motion of the nucleus nuclear shell model

18 Inside the atomic nucleuspositive charge neutral charge + proton neutron protons and neutrons are very similar, they can be classified as the same object: the nucleon Nucleons are quantum mechanical objects: They are spin ½ Fermions Radius: r ~ 1·10-15 m, or 1 fm (fermi) Charge: p → + e n → 0 Mass: p → MeV/c2 n → MeV/c2 Isospin: |p > = | -1/2 > |n > = | +1/2 >

19 proton neutron Structure of nucleons u, u, d u, d, dparticle excitations > 109 eV “Up” (u) m = 2.4 MeV/c2 q = +2/3 “Down” (d) m = 4.8 MeV/c2 q = -1/3 proton u, u, d neutron u, d, d

20 Elementary particles of the standard model

21 Terminology A – mass number gives the number of nucleons in the nucleus Z – number of protons in the nucleus (atomic number) N – number of neutrons in the nucleus A = Z + N In nuclear physics, nucleus is denoted as 𝑍 𝐴 𝑋 , where X is the chemical element e.g 𝐻 - hydrogen, 𝐶 - carbon, 𝐴𝑢 - gold. Different combinations of Z and N (or Z and A) are called nuclides nuclides with the same mass number A are called isobars nuclides with the same atomic number Z are called isotopes nuclides with the same neutron number N are called isotones nuclides with equal proton number and equal mass number, but different excited states are called nuclear isomers 7 17 𝑁 , 𝑂 , 𝐹 6 12 𝐶 , 𝐶, 𝐶 6 13 𝐶 , 𝑁 𝑇𝑎 , 𝑚 𝑇𝑎 The most long-lived non-ground state nuclear isomer is tantalum-180m, which has a half-life in excess of 1000 trillion years

22 The Chart of Nuclides - the “Playground” for Nuclear Physicsrepresentation of isotopes in the Z-N plane isotope: atom (nucleus) of an element with different number of neutrons proton number Z black: stable isotope red: +-unstable isotope blue: --unstable isotope yellow: -instable isotope green: spontaneous fission neutron number N

23 The Chart of Nuclides - the “Playground” for Nuclear Physicsrepresentation of isotopes in the Z-N plane isotope: atom (nucleus) of an element with different number of neutrons different modes of radioactive decay proton number Z neutron number N

24 The Chart of Nuclides - the “Playground” for Nuclear Physicsrepresentation of isotopes in the Z-N plane isotope: atom (nucleus) of an element with different number of neutrons proton number Z neutron number N

25 Questions: Chart of NuclidesHow are the isotopes of an element arranged on the chart? Nuclides with the same number of neutrons are called isotones. How are they arranged on the chart? Nuclides with the same mass number are called isobars. What would be the orientation of a line connecting an isobaric series? Begin with the following radioactive parent nuclei, 235U, 238U, 244Pu, trace their decay processes and depict the mode and direction of each decay process on the chart. What are the final stable nuclei?

26 Applications: Solar Abundances of ElementsSolar abundance (Si28 = 106) open questions: Big Bang fusion reactions neutron reactions Why is Fe more common than Au ? Why do the heavy elements exist and how are they produced? Can we explain the solar abundances of the elements? Mass number

27 Applications: Nuclear Astrophysics

28 Nuclear Fission: Energy and Engineering

29 Nuclear matter has exotic propertiesNuclear matter is extremely heavy ·1017 kg/m3 for comparison: sea water: ·103 kg/m3 tin oxide: ·103 kg/m3 steel: ·104 kg/m3 lead: ·104 kg/m3 core of the sun: 1.5·105 kg/m3 Although we know nuclear matter only in small portions inside atoms, it exists in nature also in big portions: Neutron Stars have a diameter of typically 10 km Nuclear structure physics investigates the response of the nucleus as a function of: 𝜌= 𝐴 𝑚 𝑝 𝜋∙ 𝑅 3 = 𝑚 𝑝 𝜋∙ 𝑟 0 3 = 1.66∙ 10 −27 𝑘𝑔 4 3 𝜋∙ 1.2∙ 10 −15 𝑚 3

30 Properties of stable nucleiRadius & shape size: nuclear radius (R = 1.2·A1/3 fm) shape: spherical / deformed (prolate / oblate) Density & mass constant nuclear density (ρ = 1017 kg/m3) nuclear mass & valley of stability Nuclear states quantum numbers spin S, parity P, magnetic moments shell structure: valence-nucleons, collective excitations Nuclear reactions binding energy: fusion & fission, nuclear astrophysics special reactions: exchange / transfer

31 Long Standing Questions of Nuclear Structure PhysicsWhat are the limits for existence of nuclei? Where are the proton and neutron drip lines situated? Where does the nuclear chart end? How does the nuclear force depend on varying proton-to-neutron ratios? What is the isospin dependence of the spin-orbit force? How does shell structure change far away from stability? How to explain collective phenomena from individual motion? What are the phases, relevant degrees of freedom, and symmetries of the nuclear many-body system? How are complex nuclei built from their basic constituents? What is the effective nucleon-nucleon interaction? How does QCD constrain its parameters? Which are the nuclei relevant for astrophysical processes and what are their properties? What is the origin of the heavy elements? p-dripline n-dripline

32 Eleven Science Questions for the 21st centuryWhat is dark matter? What is dark energy? The expansion of the universe is speeding up rather than slowing down How were the heavy elements from iron to uranium made? The production of elements up to iron in stars and supernovae is fairly understood. The precise origin of heavier elements remains a mystery. Do neutrinos have mass? The experimental discovery of neutrino oscillation implies that the neutrino has a non-zero mass. Where do ultrahigh-energy particles come from? Colliding galaxies produce extremely high energy cosmic rays which exceeds any energy produced on Earth. Is a new theory of light and matter needed to explain what happens at very high energies and temperatures? Matter and radiation appears to be well described by quantum mechanics and electromagnetism. (neutron stars, gamma-ray bursts) Are there new states of matter at ultrahigh temperatures and densities? At extremely high densities and temperatures, protons an neutrons may “dissolve” into a undifferential “soup” of quarks and gluons. Are protons unstable? The tiny imbalance between matter and antimatter at the early universe may be tied to a hypothesized instability of protons. What is gravity? Black holes are ubiquitous in the universe, and their intense gravity can be explored. Are there additional dimensions? To understand the quantum nature of gravity, one has posited the existence of space-time dimensions beyond those that we know. How did the Universe begin? There is evidence that during its earliest moments the universe underwent a tremendous burst of additional expansion (mystery)