Chapter 2. Radiation 1. Radioactivity 2. Radiation interaction with matter 3. Radiation doses and hazard assessment
Chapter 2. Radiation 1.Radioactivity 2.Radiation interaction with Matter 3.Radiation Doses and hazard Assessment
2. 1 Radioactivit 1)Overview 2) Types of radioactive decay 3) Energetics of Radioactive Decay 4)Characteristics of Radioactive decay 5)Decay Dynamics 6) Naturally occurring Radionuclides
1) Overview 2) Types of Radioactive Decay 3) Energetics of Radioactive Decay 4) Characteristics of Radioactive Decay 5) Decay Dynamics 6) Naturally Occurring Radionuclides 2.1 Radioactivity
2.2 Radiation interaction with matter Overview 2)Photon Interactions 3)Neutron Interactions 4)Interaction of Heavy Charged Particles with atter 5Scattering of electrons in a medium
1) overview 2) Photon Interactions 3) Neutron Interactions 4) Interaction of Heavy Charged Particles with Matter 5) Scattering of Electrons in a Medium 2.2 Radiation interaction with Matter
1)overview C osm Radiation is everywhere Inhaled radon Bodies Plants Radioactive elements Rocks We live in a sea of radiation
Radiation is everywhere We live in a sea of radiation… Cosmic Inhaled Radon Rocks Radioactive Elements Bodies Plants 1) overview
Discovery of Ionization by radiation Electroscopes X-rays and radioactivity discharged a charged electroscope. Curie and Rutherford attributed the discharge to the ionization of air by these rays marge 1schargea An electroscope consists of two gold leaves suspended from a metallic conductor in a glass jar
Discovery of Ionization by Radiation X-rays and radioactivity discharged a charged electroscope. Curie and Rutherford attributed the discharge to the ionization of air by these rays. Electroscopes Charged Discharged An electroscope consists of two gold leaves suspended from a metallic conductor in a glass jar
Ionization Energy of Gases The minimum energy requirea High energy particles and to remove an outer electron photons that ionise atoms and from atoms or molecules is called ionization potential molecules along their tracks in a medium are called ionizing lonizing radiation also remove radiation electrons in atomic inner shell and the average energy per ion pair is considered He+25eV→Ie++e Ionization energy He++54cV→He2++e lonization energy(IE ev) per ion pair of some substances Material Air Xe He NH3 Ge-crystal Average IE 35 22 43 39 2.9
He + 25 eV → He+ + eHe+ + 54 eV → He2+ + eIonization energy (IE eV) per ion pair of some substances Material Air Xe He NH3 Ge-crystal Average IE 35 22 43 39 2.9 The minimum energy required to remove an outer electron from atoms or molecules is called ionization potential. Ionizing radiation also remove electrons in atomic inner shell, and the average energy per ion pair is considered ionization energy Ionization Energy of Gases High energy particles and photons that ionise atoms and molecules along their tracks in a medium are called ionizing radiation
1) overview Protons Electrons Photons Heavy ions (Focused ion beam FIB): Surface atoms removed by sputterin um 50 kev electrons beam broadening below the surface I mm for \-rays, surlace exposure for optical 2 Mev protons X-Rays: requires mask Well defined path Well defined path Dose homogeneity Exponential exposure with depth
1) overview
△ Penetrating Distances Paper Plastic Lead Concrete Alpha directly lonIzing 1阝Beta radiation Gamma and x-rays indirectly Neutron ionIzing adiation
directly ionizing radiation indirectly ionizing radiation
2.2 Radiation interaction with matter Overview 2)Photon Interactions 3)Neutron Interactions 4)Interaction of Heavy Charged Particles with atter 5Scattering of electrons in a medium
1) overview 2) Photon Interactions 3) Neutron Interactions 4) Interaction of Heavy Charged Particles with Matter 5) Scattering of Electrons in a Medium 2.2 Radiation interaction with Matter
Interaction of photons with matter Photon Energies Visible red light 1.5eV visible blue light 3.0eV few eV-hundredsev X-rays 1to60ke∨ Interactions of gamma rays with matter Gamma rays ke- some Me∨ photoelectric effect Compton effect Pair productions
Interaction of Photons with Matter Photon Energies Visible red light 1.5 eV visible blue light 3.0 eV UV few eV-hundreds eV X-rays 1 to 60 keV Gamma rays keV - some MeV Interactions of gamma rays with matter: photoelectric effect Compton effect Pair productions
