Download
introduction to nuclides the big bang n.
Skip this Video
Loading SlideShow in 5 Seconds..
Introduction to Nuclides the big bang PowerPoint Presentation
Download Presentation
Introduction to Nuclides the big bang

Introduction to Nuclides the big bang

456 Vues Download Presentation
Télécharger la présentation

Introduction to Nuclides the big bang

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Introduction to Nuclidesthe big bang The big bang theory www.uwaterloo.ca/~cchieh/cact/nuctek/universe.html Einstein-Wheeler: "Matter tells space how to curve, and space tells matter how to move." 1927 Lemaitre: The universe began with an explosion based on red shift. Hubble observed the red shift proportional to distance of stars from us. 1964 Penzias and Wilson discovered the cosmic microwave background (CMB) radiation, as due to remnants of big bang. Depending on the outcome of the observations, the big bang theories will be abandoned, revised or extended to accommodate additional observartions. What is in the universe? How did the universe begin? Where did materials come from? Can material and energy really inter-convert into each other? Nuclides

  2. Nuclides

  3. The Big Bang View All energy (and matter) in the universe concentrates in a region smaller than a marble 12 billions years ago. It started to expand and cool to a billion K. Elementary particles roamed free in a sea of energy. Further expansion caused a drop in temperature and confined quarks in neutrons and protons. Galaxies began to form. Galaxy clusters Nuclides

  4. Hubble’s Observation One method for gauging distance is to observe the apparent brightness of a galaxy. The red shift shows that the universe is constantly expanding Nuclides

  5. Cosmologic Matters Radiation: massless or nearly massless, photons (light) and neutrinos. Baryonic matter (Nuclides): composed primarily of protons, neutrons and electrons; has essentially no pressure of cosmological importance. Dark matter: exotic non-baryonic matter that interacts only weakly with ordinary matter; This form of matter also has no cosmologically significant pressure. Dark energy: a bizarre form of matter, or perhaps a property of the vacuum itself; characterized by a large, negative pressure; a form of matter that can cause the expansion of the universe to accelerate Nuclides

  6. What is the history of the universe? Nuclides

  7. Nuclides composite particles of nucleons A nuclideAEZA-mass numberZ-atomic number eg.238U92 Protons and neutrons are bound together into nuclei. Atoms contain a complement of electrons. A nuclide is a type of atoms whose nuclei have a specific numbers of protons and neutrons. Nucleons (protons and neutrons) are convenient units to consider nuclear changes, although the standard model considers quarks as basic components. Like particles, nuclides are energy states, with amounts properties. Some basic principles are seen for stability of nuclide. Nuclides

  8. Stable Nuclides • Stable nuclides remain the same for an indefinite period. • Some characteristics of stable nuclides: • Atomic number Z 83, but no stable isotopes for Z = 43 and 61. • There are 81 elements with 280 stable nuclides. • Usually there are more neutrons than protons in the nuclei. • Nuclides with magic number of protons or neutrons are very stable. • Pairing of nucleons (spin coupling) contributes to nuclide stability. • Is abundance of a nuclide related to its stability? Nuclides

  9. Stable Nuclidesnumber of neutrons and protons Z = # of protons Find N / Z for 4He2 = 116O8 =40Ar18 = 91Zn40 = 144Nd60 = 186Re75 =209Bi83 = N = # of neutrons Nuclides

  10. Stable NuclidesN/Z of some light nuclides Z 14 Si Si Si 13 Al 12 Mg Mg Mg . 11 Na 10 Ne Ne Ne 9 F . 8 <- magic # . . . O O O 7 N N 6 C C . . 5 B B 4 Be . . 3 Li Li 2.He He. . 1 P D . 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ->N Nuclides

  11. Stable NuclidesN/Z of nuclides 40 Zr . . . . . . . . + . . . XXX X X 39 Y X38 Sr X XXX 37 Rb X X 36 Kr X X XX X 35 Br . . . . . + . . X X34 Se XXXX X X 33 As X 32 Ge X XXX X . 31 Ga X X30 Zn . . . + . X XXX X . 29 Cu X X28 Ni X XXX X . . 27 Co X26 Fe X XXX . . 25 Mn + X24 Cr X XXX . . 23 v XX22 Ti XXXXX . . . 21 Sc X 20 Ca X X 2 2 3 4 5 01234567890123456789012345678901 N / A ratio increases as A increases More stable isotopes for even Z than odd Z More stable isotones for even N than odd N More stable isotopes and isotones for magic Z and N Nuclides

  12. Stable Nuclidesnatural occurring heavy nuclides Natural Occurring Isotopes of Heavy Elements (abundance) 76 Os 184 (0.018), 186 (1.59), 187 (1.64), 188 (13.3), 189 (16.1), 190 (26.4), 192 (41.0)77 Ir 191 (38.5), 193 (61.5)78 Pt 190 (0.0127), 192 (0.78), 194 (32.9), 195 (33.8), 196 (25.2), 198 (7.19)79 Au 197 (100)80 Hg 196 (0.146), 198 (10.02), 199 (16.84), 200(23.13), 201(13.22), 202(29.8), 204(6.85)81 Tl 203 (29.5), 205 (70.5)82 Pb 204 (1.4), 206 (25.1), 207 (21.7), 208 (52.3)83 Bi 209 (100)90 Th 232 (100% half life 1.4x1010 y)92 U 235 (0.720, half life 7.04x108 y), 238 (99.276, half life 4.5x109 y) Nuclides

  13. Stable Nuclidespairing of nucleons Two protons or neutrons occupy a quantum state, due to their ½ spin. Pairing nucleons stabilises nuclides, leading to a large number of stable nuclides with even Z and N. No stable isotopes for Z = 43 or 61. No stable isotones with N = 19, 31, 35, 39, 61, 89 More stable isotopes for even Z than odd Z and for even N than odd N Elements with even Z are more abundant than those with odd Z of comparable mass. Effect of Paring Nucleons Z N # of stable stable nuclides even even 166 even odd 57 odd even 53 odd odd *4 total280 *They are: 2D1, 6Li3, 10B5, & 14N7 Nuclides

  14. Stable Nuclidesmagic numbers of nucleons Magic numbers are 2, 8, 20, 28, 50, 82, and 126. Double-magic number nuclides: 4He2, 16O8, 40Ca20, 48Ca20, & 208Pb82. 4He2 as alpha particles, abundant in the universe, 16O8 abundant on Earth. Six stable isotopes of Ca20, 5 stable isotopes of Ni28, high for their masses. Large number of stable isotopes and isotones with Z & N = 50 and 82. The heavies stable nuclide 209Bi83 has 126 neutrons. O8, Ca20, Ni28, Sn50 and Pb82 have relative high abundance. Nuclides

  15. Stable Nuclidesabundances of elements Even Z elements are more abundant than odd Z ones of comparable mass. Nuclides

  16. Stable and Radioactive Nuclidesmass and stability of nuclides Mass and energy are equivalent, E = m c2. Relative mass is the key for stability of nuclides. Energy drives changes. If a system can lower its energy, it will. Unstable nuclides undergo decay or fission, releasing energy stabilises the system. Discuss the stability of carbon isotopes. Half life 9C 127. ms 10C 19.3 s 11C 20.3 m 12C stable 13C stable 14C 5730. y 15C 2.45 s 16C 0.75 s Nuclides

  17. Stable and Radioactive Nuclidesbinding energy • The binding energy (BE) of a nuclide is the energy released when the atom is synthesized from the appropriate numbers of hydrogen atoms and neutrons. • Z H + N n = AEZ + BE • or ZmH + Nmn = mE + BEwhere mH, mn, and mE are masses of H, n, and AEZ respectively.Eg • BE = ZmH + Nmn - mE • BE (3He) = (2*1.007825 + 1.008665 - 3.01603) 931.481 MeV = 7.72 MeV • BE (4He) = (2*1.007825 + 2*1.008665 - 4.00260) 931.481 MeV = 28.30 MeV Nuclides

  18. Stable and Radioactive Nuclidesaverage binding energy The binding energy and averagebinding energy of some nuclides Nuclide BEBE / A MeV MeV / nucleon 3He2 7.72 2.574He2 28.3 7.0816O8 127.6 7.9856Fe26 492.3 8.79 54Fe26 471.76 8.74 208Pb82 1636.44 7.87 238U92 1801.7 7.57 BE A A Nuclides

  19. The Average Binding Energy Curve Nuclides

  20. Stable and Radioactive Nuclidesmass excess (ME) The difference between the mass of a nuclide and its mass number, A, is the mass excess (ME),ME = mass - A. Masses (amu) of some entities H 1.00782503 18O 17.99916 2D 2.014102 54Fe 54.938296 3H 3.016049 56Fe 55.934939 4He 4.002603 206Pb 205.975872 12C 12.000000 209Bi 208.9804 14C 14.003242 235U 235.043924 16O 15.994915 238U 238.055040 What are the MEs for the nuclides listed here? Which is the standard? Which have negative MEs? Nuclides

  21. Stable and Radioactive Nuclidesmass excess (ME) and average -BE Comparison of mass excess and average binding energy (amu) Nuclide MassME -BE average BE H 1.007825 0.007825 0 0 n 1.008665 0.008665 0 03He 3.01603 0.01603 -0.00276 0.008284He 4.00260 0.00260 -0.0076 0.030412C 12.000000 0 -0.00825 0.0989416O 15.994915 -0.005085 -0.00857 0.136940Ca 39.96259 -0.03741 -0.00917 0.3669 54Fe 53.939612 -0.060388 -0.00938 0.506556Fe 55.934939 -0.065061 -0.00944 0.52851208Pb82 207.976627 -0.023373 -0.00845 1.757238U92 238.050784 0.050784 -0.00813 1.934 Nuclides

  22. Stable and Radioactive Nuclidesfission and fusion energy and ME Nuclides

  23. Stable and Radioactive Nuclidesapplication of mass excess (ME) Like masses, the ME can be used to calculate energy of decay, because the same scale is used for both. eg: ME’s of 40Sc21 and 40Ca20 are -20.527 and -34.847 MeV respectively. Estimate the energy of decay for 40Sc2140Ca20 + b+ or 40Sc21 + e–40Ca20solution: Edecay = -20.527 - (-34.847) = 14.32 MeV Edecay includes 1.02 MeV for the positron-electron pair for b+ decay. Nuclides

  24. Stable and Radioactive NuclidesME of isobars ME Mass excesses (amu) of isobars with mass number 123: Z In49 Sn50Sb51 Te52 I-53 Xe54 Cs55 Ba56-0.0896 -0.0943 -0.0958 -0.0967 -0.0944 -0.0915 -0.0870 -0.0808 Nuclides

  25. Stable and Radioactive NuclidesBE of isobars Plots of BE an ME are very similar, and either one can be used to show the decay of isobars. Only 57Fe26 is stable for isobars of mass 57 .Mass.BE .amu .amu Cr24 56.9434 0.53031 Mn25 56.9383 0.53462 Fe26 56.9354 0.53667 Co27 56.9363 0.53493 Ni28 56.3980 0.53240 Nuclides

  26. Stable and Radioactive Nuclidesproblem types Evaluate the BE of a nuclide tell nuclide with zero BE evaluate ME of a nuclide tell nuclide with zero ME evaluate decay energy estimate decay mode predict the stable isobar(s) estimate max kinetic energy of beta or positrons in beta decay Mass and BE of mass 57 isobars .Mass .BE .amu .amu Cr24 56.9434 0.53031 Mn25 56.9383 0.53462 Fe26 56.9354 0.53667 Co27 56.9363 0.53493 Ni28 56.3980 0.53240 Nuclides

  27. Stable and Radioactive NuclidesME of isobarscontinue Pairing of nucleons plays a role for stability of isobars with even mass numbers. There are even-even and odd-odd type of nuclides in isobars of even mass numbers Nuclides

  28. Stable and Radioactive Nuclidesa semi-empirical equation for BE Instability due to p Pairing of nucleon Proportional to A BE(A,Z) = 14.1A- 13A2/3- - + Ea Instability due to neutron to proton ratio Decrease due to surface tension Nuclides

  29. Nuclidessummary The big bang Factors for stable nuclides mass and stability Nuclides