1. IAEA Sources of Radiation Natural Radiation - Cosmic Radiation Day 3 – Lecture 8 1

2. IAEA Objective To learn about the Cosmic radiation from space, cosmogenic radionuclides, variance of cosmic radiation with latitude and altitude, and exposure from cosmic radiation 2

3. IAEA Content  Cosmic radiation  Cosmogenic radionuclides  Radiation variance with latitude and altitude  Dose rates from cosmic radiation 3

4. IAEA Types of Cosmic Radiation  Primary cosmic radiation  Secondary cosmic radiation 4

5. IAEA Primary Cosmic Radiation  Made up of extremely high energy particles (up to 10 18 eV)  Composed mostly of protons or sometimes larger particles  Large percentage comes from outside solar system  Some comes from sun in form of solar flares 5

6. IAEA Secondary Cosmic Radiation  Produced by interaction of primary cosmic radiation with the atmosphere  Is what we actually receive here on Earth  Lower energy radiations in the form of photons, electrons, neutrons, and muons 6

7. IAEA Background Radiation Galactic radiation is a component of the background radiation on earth.

8. IAEA Background Radiation Cosmic radiation contributes to the background radiation on earth. The earth’s atmosphere provides shielding from most of the cosmic radiation.

9. IAEA Background Radiation. The dose from cosmic radiation is reduced at lower altitude due to the additional shielding by the earth’s atmosphere.

10. IAEA Cosmogenic Radionuclides NuclideHalf-lifeSourceNatural Activity 14 C5730 yrCosmic-ray interactions, 14 N(n,p) 14 C 0.22 Bq/g 3H3H12.3 yrCosmic-ray Interactions with N and O 1.2 x 10 -3 Bq/kg 7 Be53.3 daysCosmic-ray Interactions with N and O 0.01 Bq/kg

11. IAEA Cosmic Ray Doses Subsonic Flight at 11 km Route Flight Duration (hrs) Dose per round trip (  Gy) Los Angeles – Paris 11.148 Chicago – Paris 8.336 New York - Paris 7.431 New York - London 7.029 Los Angeles - New York 5.219 Sydney - Acapulco 17.444

12. IAEA Cosmic Ray Doses Supersonic Flight at 19 km Route Flight Duration (hrs) Dose per round trip (  Gy) Los Angeles – Paris 3.837 Chicago – Paris 2.826 New York – Paris 2.624 New York – London 2.422 Los Angeles - New York 1.913 Sydney - Acapulco 6.221

13. IAEA Typical Cosmic Ray Dose Rates  4 x 10 -8 Sv/hr at ground level in Northeastern US  2 x 10 -7 Sv/hr at 4.6 km altitude  3 x 10 -6 Sv/hr at 16.8 km altitude 13

14. IAEA Natural Radiation Exposure Around the World 14

15. IAEA Effective Dose Equivalent to a Member of the Population of the United States Source Average Annual Effective Dose Equivalent  Sv mrem Inhaled (radon and decay products)2000200 Other Internbally Deposited Radionuclides 39039 Terrestrial Radiation28028 Cosmic Radiation27 Cosmogenic Radioactivity101 Rounded Total from Natural Sources3000300 Rounded Total from Artificial Sources60060 Total3600360 15

16. IAEA Sources of Radiation Exposure In the United States 16

17. IAEA Where to Get More Information  Cember, H., Johnson, T. E, Introduction to Health Physics, 4th Edition, McGraw-Hill, New York (2009)  UNSCEAR, Sources and Effects of Ionizing Radiation, 2008 Report to the General Assembly with Scientific Annexes, United Nations, New York, 2008  International Atomic Energy Agency, Postgraduate Educational Course in Radiation Protection and the Safety of Radiation Sources(PGEC), Training Course Series 18, IAEA, Vienna (2002) 17