physicscatalyst.com logo






Radioactivity






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
    p->n+e+
  • 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 Home page Class 12 Physics Home page