1. 4/2003 Rev 2 I.2.4 – slide 1 of 9 Session I.2.4 Part I Review of Fundamentals Module 2Basic Physics and Mathematics Used in Radiation Protection Session 4Internal Conversion and Auger Electrons IAEA Post Graduate Educational Course Radiation Protection and Safety of Radiation Sources

2. 4/2003 Rev 2 I.2.4 – slide 2 of 9  In this session we will discuss the process of Internal Conversion  We will also discuss Auger Electrons Overview

3. 4/2003 Rev 2 I.2.4 – slide 3 of 9 Auger Electrons  Auger electrons are a special case of Internal Conversion.  During the Internal Conversion Process, a gamma photon from the nucleus interacts with and transfers all of its energy to a tightly bound (K-shell) orbital electron.  The electron is ejected from the atom with considerable energy, equal to that of the initial gamma photon minus the binding energy.

4. 4/2003 Rev 2 I.2.4 – slide 4 of 9 Auger Electrons characteristic X-rayAuger electron

5. 4/2003 Rev 2 I.2.4 – slide 5 of 9 Auger Electrons E γ = 296 keV E ceK = keV E ceK = 217.6 keV E ceL3 = 284.4 keV E ceM = 293.3 keV BE K-shell = E ceK - E γ = 217.6 - 296 = - 78.4 keV 217.6 - 296 = - 78.4 keV BE L3-shell = E ceL3 - E γ = 284.4 - 296 = - 11.6 keV 284.4 - 296 = - 11.6 keV BE M-shell = E ceM - E γ = 293.3 - 296 = - 2.7 keV

6. 4/2003 Rev 2 I.2.4 – slide 6 of 9 Auger Electrons BE K-shell = E ceK - E γ = 217.6 - 296 = - 78.4 keV 217.6 - 296 = - 78.4 keV BE L3-shell = E ceL3 - E γ = 284.4 - 296 = - 11.6 keV 284.4 - 296 = - 11.6 keV NOTE: gamma, X-ray and electron energies are positive while binding energies are negative K α1 characteristic X-ray = - 11.6 – (- 78.4) = 66.8 keV

7. 4/2003 Rev 2 I.2.4 – slide 7 of 9 Auger Electrons E γ = 296 keV E ceL2 = 282.7 keV BE L2 = E ceL2 - E γ = 282.7 - 296 = - 13.3 keV 282.7 - 296 = - 13.3 keV BE M = E ceM - E γ = 293.3 - 296 = - 2.7 keV 293.3 - 296 = - 2.7 keV characteristic X-ray (M  L) = BE M - BE L2 = BE M - BE L2 = - 2.7 - (- 13.3) = 10.6 keV = - 2.7 - (- 13.3) = 10.6 keV

8. 4/2003 Rev 2 I.2.4 – slide 8 of 9 Auger Electrons From previous slide: BE M = - 2.7 keV characteristic X-ray (M  L) = 10.6 keV Auger electron ejected from the M-shell = 10.6 – 2.7 = 7.9 keV (close to 7.4 keV) (close to 7.4 keV)

9. 4/2003 Rev 2 I.2.4 – slide 9 of 9 Where to Get More Information  Cember, H., Johnson, T. E., Introduction to Health Physics, 4th Edition, McGraw-Hill, New York (2008)  Martin, A., Harbison, S. A., Beach, K., Cole, P., An Introduction to Radiation Protection, 6 th Edition, Hodder Arnold, London (2012)  Jelley, N. A., Fundamentals of Nuclear Physics, Cambridge University Press, Cambridge (1990)  Firestone, R.B., Baglin, C.M., Frank-Chu, S.Y., Eds., Table of Isotopes (8 th Edition, 1999 update), Wiley, New York (1999)