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Flashcards in More about radiation Deck (10):

α radiation consists of:

Positively charged particles. Composed of 2 protons and 2 neutrons.


β radiation from naturally occuring radiation consists of:

Fast moving electrons.


γ consists of:

Photons with a wavelength of the order of 10-11.


What is intensity

The radiation energy per second normally through a unit area.


For a source emitting n photons per second the intensity =

Radiation energy per second/total area = nhf/4πr2


Alpha decay

  • Αlpha emitters tend to be heavier isotopes 
  • Alpha particle is stable within nucleus, does not always escape first time 
  • A reduces by 4, Z reduces by 2 
  • The greater the alpha particles energy, the shorter the half-life of the isotope


Positron emission (β+) decay 

  • In a proton rich nucleus
  • A proton becomes a neutron .
  • A does not change 
  • Z reduces by 1


Beta (β−) decay 

  • In a neutron rich nucleus
  • A neutron becomes a proton.
  • A does not change 
  • Z increases by 1


Electron capture 

  • A proton rich nuclei captures an inner-shell electron.
  • Proton changes into a nuetron with the emission of an electron neutrino
  • Daughter nuclide/nucleus/atom may be excited 
  • Orbiting electron drops down to fill vacancy left by captured electron 
  • X-ray photon emitted by the atom


Gamma emission

There is no change in the number of protons and neutrons during gamma emission.

A photon is emitted if a nucleus has excess energy after alpha or beta decay.