6) β Decay

  • There are two types of β decay , β- and β+
  • In β decay an nucleus decay spontaneously emitting an electron or positron
  • Under β- decay one of the neutrons in the parent nucleus gets transformed into a proton and in the process an electron and an antineutrino are emitted
    n-> p+e--
  • The daughter nucleus thus formed in β- decay would be an element one place to the right of the parent in the periodic table of elements
  • Examples of β- decay

  • β- is common over entire range of nuclides and amongst the naturally occurring heavy radioactive nuclides and in fission products
  • In β+ decay one the protons of the parent nucleus gets transformed into a neutron emitting a positron and neutrino
  • In β+ decay the daughter nucleus would be one place to the left of parent nuclei in the periodic table
  • Examples of β+ decay

  • In both β+ and β- symbol ν- and ν represents antineutrino and neutrino
  • Both antineutrino (ν-) and neutrino(ν) are charge less and nearly less particles and interact very weakly with matter which make their detection very difficult

  • In these β decay( β+ and β-) mass number A of nucleus remain same after the decay

7) γ Decay

  • After alpha or beta decay processes it is common to find the daughter nucleus to be in an excited state
  • Just like atoms ,nucleus also have energy levels
  • So an nucleus in excited state can make transitions from higher energy levels to lower one by the emission of electro magnetic radiation
  • The energy difference in allowed energy levels of a nucleus are of the order of Mev and the photons emitted by nuclei have energies of the order of Mev and are called γ rays
  • As an example,β decay of 60Co27 nucleus gets transformed into 60Ni28 nucleus in excited state which then de -excites to its ground state by successive emission of 1.17 Mev and 1.33 Mev gamma rays as shown in energy level diagram,

Class 12 Maths Class 12 Physics