1. Beta Decay Contents: What it is (Maximum) Energy of radiation from mass defect Beta-(Maximum) Energy of radiation from mass defect Beta- Whiteboard (Maximum) Energy of radiation from mass defect Beta+(Maximum) Energy of radiation from mass defect Beta+ Whiteboard Reverse decay: electron capture Enrico Fermi, Wolfgang Pauli, and the “little neutral one”Enrico Fermi, Wolfgang Pauli, and the “little neutral one”

2. TOC 60 27 Co 60 28 Ni +  - + Beta Decay: 13 7 N 13 6 C +  + + Conservation of charge Beta minus - electron “As if” neutron -> proton + electron Beta plus - positron “As if” proton -> neutron + positron Particles are “of the nucleus” (not orbital) - Neutrino, (anti neutrino) - fudge

3. Beta- Decay - Maximum energy of beta particle TOC Calculating mass defect of beta decay 60 27 Co --> 60 28 Ni + Beta- + (Anti) Neutrino 59.933820 -->59.930789 +Energy (Look up masses of these in appendix F) (Mass on right includes 28 electrons) Mass defect = parent - products = 59.933820 - 59.930789 Mass “defect” =.003031 u Kinetic energy = (.003031 u)(931.5 MeV/u) = 2.823 MeV This is a maximum - the neutrino carries away some (nucleus as well)

4. Whiteboards: Beta- Maximum Energy 11 | 22 TOC

5. W Parent mass = 23.990961 u Product mass = 23.985042 u Mass defect = parent - products = 0.005919 u Energy of radiation = (0.005919 u)(931.5 MeV/u) = 5.51 MeV 24 11 Na --> 24 12 Mg +  - + (anti) 23.990961 -->23.985042 What is maximum energy of Beta-? (in MeV) 5.51 MeV

6. W 31 14 Si --> 31 15 P +  - + (anti) 30.975362--> 30.973762 What is maximum energy of Beta -? (in MeV) 1.49 MeV Parent mass = 30.975362 u Product mass = 30.973762 u Mass defect = parent - products = 0.001600 u Energy of radiation = (0.001600 u)(931.5 MeV/u) = 1.49 MeV

7. Beta+ Decay - Maximum energy of beta+ TOC Calculating mass defect of beta+ decay 13 7 N ---> 13 6 C + Beta+ + Neutrino 13.005738 -->13.003355 + 2m e +Energy (Carbon 6 mass includes only 6 electrons, we add two - orbital, Beta ) 13.005738 -->13.003355 + 2(.00054858 u) +Energy 13.005738 -->13.00445216 +Energy Mass defect = parent - products = 13.005738 - 13.00445216 Mass “defect” = 0.00128584 u Kinetic energy = (0.00128584 u)(931.5 MeV/u) = 1.20 MeV This is a maximum - the neutrino carries away some (nucleus as well)

8. Whiteboards: Beta+ Maximum Energy 11 | 22 TOC

9. W Parent mass = 15.003065 u Product mass = 15.000108 + 2(.00054858) = 15.00120516 Mass defect = parent - products = 0.00185984 ene rgy of radiation = (0.0018598)(931.5 MeV/u) = 1.732 MeV 15 8 O --> 15 7 N +  + + 15.003065 -->15.000108+ 2(.00054858) What is maximum energy of Beta+? (in MeV) 1.732 MeV

10. W 40 19 K --> 40 18 Ar +  + + 39.964000--> 39.962384 + 2(.00054858) What is maximum energy of Beta+? (in MeV) 0.4833 MeV Parent mass = 39.964000 u Product mass = 39.962384 u + 2(.00054858) = 39.96348116 Mass defect = parent - products = 0.00051884 u Energy of radiation = (0.00051884)(931.5 MeV/u) = 0.4833 MeV

11. Reverse Beta - electron capture TOC Nucleus captures inner shell electron Proton becomes neutron Product less massive than parent and electron Energy is released as neutrino X-rays observed as electron jumps down to fill inner shell 7 4 Be + e- --> 7 3 Li +

12. Pauli, Fermi, and the little neutral one TOC Beta decay products were missing energy Pauli proposes a particle is carrying away energy Fermi names it Neutrino - “Little neutral one” - It. Neutrinos confirmed in 1956, no surprise Enrico Fermi 1901-1954 Wolfgang Pauli 1900-1958

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