Transcription
Selected Topics in Nuclear PhysicsLecturer: Hans-Jürgen Wollersheime-mail: h.j.wollersheim@gsi.deweb-page: https://web-docs.gsi.de/ wolle/ and click onHans-Jürgen Wollersheim - 2022
Literature Recommended Textbook Supplemental Textbookwww.bookzz.orgHans-Jürgen Wollersheim - 2022
neutron starunstable nucleisupernovaesunheavy ionnuclear reactionsHans-Jürgen Wollersheim - 2022
Brief historical overviewin search of the building blocks of the universe .Greek philosophers4 building blocksearthairwaterfire5th BC - Democritusatomic hypothesis18th – 19th century Lavoisier, Dalton, .put atomic hypothesis on firm basisdistinction between compounds and pure elements1896 Dmitri Mendeleev92 building blocks(chemical elements)1H, 2He,. 92UHans-Jürgen Wollersheim - 2022
Brief historical overviewin search of the building blocks of the universe .1896 Henri Becquereldiscovers ion of radiation from atoms3 types observed: α, β and γα and β deflected in opposite directionopposite chargesα deflected less than βα must have larger massγ not deflecteduncharged 1900 Ernest Rutherfordelectron“. it was as incredible as if you hadfired a 15-inch shell at a piece of tissuepaper and it came back and hit you”investigates new radiationα and β emissions change nature of elementα‘s charge 2eα‘s mass 4Hβ radiation electronsγ electromagnetic radiation (photons)1911 Ernest Rutherford tests Thomson’s model of the atomN electrons (-e·N) embedded in ( e·N) chargeuniformly distributed over atomic volume“plum pudding model”Hans-Jürgen Wollersheim - 2022expectedα’s (2He) pushed a little to theside by charges of atom (79Au)observedsome α’s deflectedbackwards to 1800!!
Brief historical overviewin search of the building blocks of the universe1913 Niels Bohrplanetary model of atomall positive charges (and all mass)concentrated in tiny region at the centerclassical physics: electron should fall into the nucleus1920 Francis William Aston mass spectrographmeasures masses of atomsNew mechanism is neededmasschargeHe 4 HHe 2 HC 12 HC 6H𝐸𝐸O 16 HO 8Hhypothesis of neutral particle in nucleus with m mp1925 Werner Heisenbergquantum mechanicssimplest atom Hits nucleus protonelectron cloud1932 James Chadwickdiscovers the neutron3 building blockselectron proton neutronNUCLEAR PHYSICSHans-Jürgen Wollersheim - 2022𝐵𝐵
Brief historical overviewin search of the building blocks of the universe1932 Enrico Fermideveloped the theory of β-decay1934 Irene Joliot-Curie & Frederic Joliotartificial radioactivity1934 Hans Bethe2713𝐴𝐴𝐴𝐴 42𝐻𝐻𝐻𝐻 30 15𝑃𝑃 1𝑛𝑛liquid drop model and mass formula1938 Otto Hahn, Lise Meitner & Fritz Strassmanndiscover nuclear fission1948 Maria Goeppert-Mayer & J. Hans D. Jensendevelop the nuclear shell modelHans-Jürgen Wollersheim - 2022
Brief historical overviewin search of the building blocks of the universe1953 Aage Niels Bohr, Ben Roy Mottelson, Leo James Rainwaterdeveloped the collective nuclear model1956 Frederick Reines & Clyde L. Cowandiscovery of the neutrino1983 Carlo Rubbiadiscovery of the W and Z Boson1998 Takaaki Kajita & Arthur B. McDonalddiscovery of neutrino oscillationsneutrinos must have some massHans-Jürgen Wollersheim - 2022
Scales in the UniverseSo . Where Do We Start?We need a point of reference to start discussing nuclear physics.crystalmoleculeatomnucleusHans-Jürgen Wollersheim - 2022protonquark
The atomatomic excitations 1-105 eV atom is a neutral systemcaused by transitionsbetween electronic states 10-10 mHans-Jürgen Wollersheim - 2022
Bohr atomic modelabsorption spectrumHydrogen gasHydrogenabsorptionspectrumHans-Jürgen Wollersheim - 2022
Bohr atomic modelemission spectrumHeliumemissionspectrumHans-Jürgen Wollersheim - 2022
The atomic nucleusnuclear excitations 105-108 eVcaused by transitionsbetween nuclear statesproton (π) neutron (ν) 10-15 m fmexcitations can be causedby individual nucleons oras a collective motion ofthe nucleusnuclear shell modelHans-Jürgen Wollersheim - 2022
Inside the atomic nucleuspositive chargeneutral charge protonneutronprotons and neutrons are very similar, they can be classified as the same object: the nucleonNucleons are quantum mechanical objects: They are spin ½ Fermions Radius: r 1·10-15 m, or 1 fm (fermi) Charge: p en 0 Mass:p 938.27 MeV/c2n 939.56 MeV/c2 Isospin: p -1/2 n 1/2 Hans-Jürgen Wollersheim - 2022
Structure of nucleonsparticle excitations 109 eV“Up” (u)m 2.4 MeV/c2q 2/3“Down” (d)m 4.8 MeV/c2q -1/3protonneutronu, u, du, d, dHans-Jürgen Wollersheim - 2022
Elementary particles of the standard modelHans-Jürgen Wollersheim - 2022
TerminologyA – mass number gives the number of nucleons in the nucleusZ – number of protons in the nucleus (atomic number)N – number of neutrons in the nucleusA Z N𝐴𝐴𝑋𝑋In nuclear physics, nucleus is denoted as 𝑍𝑍 , where X is the chemical elemente.g. 11𝐻𝐻 - hydrogen, 126𝐶𝐶 - carbon, 19779𝐴𝐴𝐴𝐴 - gold.Different combinations of Z and N (or Z and A) are called nuclides nuclides with the same mass number A are called isobarsnuclides with the same atomic number Z are called isotopesnuclides with the same neutron number N are called isotonesnuclides with equal proton number and equal mass number,but different excited states are called nuclear isomers1717177𝑁𝑁, 8𝑂𝑂, 9𝐹𝐹12 13 146𝐶𝐶, 6𝐶𝐶, 6𝐶𝐶13 146𝐶𝐶, ��𝑇𝑇The most long-lived non-ground state nuclear isomer is tantalum-180m, which has a half-life in excess of 1000 trillion yearsHans-Jürgen Wollersheim - 2022
The Chart of Nuclides- the “Playground” for Nuclear Physicschart of nuclides:-representation of isotopes in the Z-N planeproton number Z-isotope: atom (nucleus) of an element withdifferent number of neutronsblack: stable isotopered:β -unstable isotopeblue: β--unstable isotopeyellow: α-instable isotopegreen: spontaneous fissionneutron number NHans-Jürgen Wollersheim - 2022
The Chart of Nuclides- the “Playground” for Nuclear Physicschart of nuclides:-representation of isotopes in the Z-N planeproton number Z-isotope: atom (nucleus) of an element withdifferent number of neutronsdifferent modes ofradioactive decayneutron number NHans-Jürgen Wollersheim - 2022
The Chart of Nuclides- the “Playground” for Nuclear Physicschart of nuclides:-representation of isotopes in the Z-N planeproton number Z-isotope: atom (nucleus) of an element withdifferent number of neutronsneutron number NHans-Jürgen Wollersheim - 2022
Applications: Solar Abundances of ElementsSolar abundance (Si28 106)Big Bang fusion reactionsneutron reactionsopen questions: Why is Fe more commonthan Au ? Why do the heavy elementsexist and how are theyproduced? Can we explain the solarabundances of the elements?Mass numberHans-Jürgen Wollersheim - 2022
r-process abundancesShell evolution, Nucleosynthesis (r-process)exp.pronounced shell gapshell structure quenchedmass number AAssumption of N 82 and N 126 shell quenching leads to a considerableimprovement in the global abundance fit in r-process calculationsHans-Jürgen Wollersheim - 2022
Nuclear Fission: Energy and EngineeringHans-Jürgen Wollersheim - 2022
Nuclear matter has exotic properties Nuclear matter is extremely heavy2.3·1017 kg/m3for comparison: sea water:1.0·103 kg/m3 tin oxide:1.6·103 kg/m3 steel:1.1·104 kg/m3 lead:2.5·104 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 theresponse of the nucleus as a function of:𝜌𝜌 𝐴𝐴𝑚𝑚𝑝𝑝𝑚𝑚𝑝𝑝1.66 10 27 𝑘𝑘𝑘𝑘 4 3 𝜋𝜋 𝑅𝑅3 4 3 𝜋𝜋 𝑟𝑟03 4 3 𝜋𝜋 1.2 10 15 𝑚𝑚3Hans-Jürgen Wollersheim - 2022
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 stabilityNuclear states quantum numbers spin S, parity P, magnetic moments shell structure: valence-nucleons, collective excitationsNuclear reactions binding energy: fusion & fission, nuclear astrophysics special reactions: exchange / transferHans-Jürgen Wollersheim - 2022
Long Standing Questions of Nuclear Structure Physics What 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-neutronratios?- 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, andsymmetries of the nuclear many-body system?p-dripline 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 processesand what are their properties?- What is the origin of the heavy elements?Hans-Jürgen Wollersheim - 2022n-dripline
Nuclear units and physical constantsNuclear units length unit:Fermi femtometer fm 10-15Albert Einstein1879-1955Nobel price 1921[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] 931.49432 MeV/c2 1.66054·10-27 [kg] time unit:[s] or [fm/c] 3·10-24 [s]𝐸𝐸 𝑚𝑚 𝑐𝑐 2Constant of nature relevant to nuclear physics speed of light in vacuum, c 2.99792458·108 [m/s]Planck’s constant / 2π ħ 6.58211889·10-22 [MeV s] 1.054·10-34 [J s]ħc 197.3269602 [MeV fm]fine structure constant (dimensionless), α e2/(ħc) 1/137.0359976 e2 α·ħc 1.4399643929 [MeV fm]elementary charge, e 1.602·10-19 [C] or e 1.1999851636 𝑀𝑀𝑀𝑀𝑀𝑀 𝑓𝑓𝑓𝑓rest energy of proton, mpc2 938.27231 [MeV]rest energy of neutron, mnc2 939.56563 [MeV]rest energy of electron, mec2 0.51099906 [MeV]Avogadro’s number, NA 6.0221367·1023 /mol E – p relationship:Kinetic energy:𝐸𝐸 2 𝑝𝑝2 𝑐𝑐 2 𝑚𝑚0 2 𝑐𝑐 4𝑇𝑇 𝐸𝐸 𝑚𝑚0 𝑐𝑐 2 𝑚𝑚0 𝑐𝑐 2 𝛾𝛾 1Hans-Jürgen Wollersheim - 2022
www.bookzz.org. Hans-Jürgen Wollersheim - 2022 neutron star. supernovae. sun. heavy ion. nuclear reactions. unstable nuclei. Hans-Jürgen Wollersheim - 2022 Brief historical overview in search of the building blocks of the universe . earth. water. air. fire. Greek philosophers. 4 building blocks. 5. th. BC - Democritus atomic hypothesis . 18. th - 19. th. century Lavoisier, Dalton .
