Radiation Friend or Foe? Saturday Physics for Everyone 7 Oct 2017 Kevin Pitts
Thank you Toni for 14 years of Saturday Physics, and your service to our students. 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) link 2
Outline What is radiation? Discuss different types Where we encounter radiation How does radiation affect us? The good and the bad 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 3
Question Would you eat food that has been irradiated? What s scary about radiation? 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 4
Radiation Definition: the emission of energy as electromagnetic waves or as moving subatomic particles, especially high energy particles that cause ionization. 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 5
Radiation Definition: the emission of energy as electromagnetic waves or as moving subatomic particles, especially high energy particles that cause ionization. Radiation carries energy Energy example: slow/fast car, slow/fast bus 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 5
Radiation Definition: the emission of energy as electromagnetic waves or as moving subatomic particles, especially high energy particles that cause ionization. Radiation carries energy Energy example: slow/fast car, slow/fast bus 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 5
Radiation Definition: the emission of energy as electromagnetic waves or as moving subatomic particles, especially high energy particles that cause ionization. Different types: EM or subatomic particles 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 5
Radiation Definition: the emission of energy as electromagnetic waves or as moving subatomic particles, especially high energy particles that cause ionization. High energy radiation causes ionization 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 5
Radiation Definition: the emission of energy as electromagnetic waves or as moving subatomic particles, especially high energy particles that cause ionization. Start with electromagnetic waves. 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 5
Electromagnetic Spectrum Faraday cage and radio 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 11
Infrared heat radiation IR camera The Predator could see Arnold in the infrared 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 12
Infrared radiation Objects radiate in the infrared It s a way to cool off! Any ideas about what else cools itself by emitting IR radiation? 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 13
Electromagnetic Spectrum microwave Non-ionizing. Energy too low to break atomic bonds 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 14
Can cell phones cause brain cancer? Cell phone frequency bands About 10 9 Hz (1 GHz) 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 15
Electromagnetic Spectrum microwave Non-ionizing. Energy too low to break atomic bonds Ionizing! 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 16
Ionizing radiation DNA double helix Can break chemical bonds Can break DNA strands Mutations! Can be: bad (cancer, birth defects) or good (cancer treatment, polymer creation) Fortunately, for DNA we have autocorrect. 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 17
X rays Penetrate very deeply (great for imaging!) Ionizing enough energy to break bonds Radiation dose from 1 x ray tiny 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 18
Ultraviolet radiation is ionizing UV exposure (not visible or IR) can cause skin cancer. 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 19
More radiation, more cancers Linear effect: bigger dose, cancer more likely Measured (mostly) from atomic bombs Sv = Sievert 100 rem=1 Sv Typical person (per year): 300mrem=0.3rem=0.003Sv 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 20
Radiation Definition: the emission of energy as electromagnetic waves or as moving subatomic particles, especially high energy particles that cause ionization. Radiation carries energy Energy example: slow/fast car, slow/fast bus Different types: EM or subatomic particles High energy radiation causes ionization 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 21
Radioactivity When atoms (nuclei) produce radiation. 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 22
Alpha decay Geiger counter Alpha particle is really a helium nucleus. Helium safe (balloons! squeaky voices!) so why is alpha radiation potentially dangerous? 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 23
Beta radiation TV+magnet Beta particle is really an electron. Electrons safe (electricity!) so why is beta radiation potentially dangerous? Example: 14 C 14 N + 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 24
Radiation from space Earth s atmosphere and magnetic field protect us from cosmic radiation. Cloud chamber Link link 7-Oct-2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 25
National Research Council At the present time, given current knowledge, the level of radiation astronauts would encounter would not allow a human crew to undertake a Mars mission and might also seriously limit long term Moon activity. International Space Station astronauts receive a radiation dose that is 27 times higher than we receive on Earth s surface. The ISS is still protected by Earth s magnetic field and upper atmosphere. 7-Oct-2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 26
Radiation Radiation would be sufficient to kill humans in long duration space flight, unless an acceptable shielding method was developed. Perhaps other beings might be less susceptible to radiation effects. 7-Oct-2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 27
Sources/Defenses Estimate your annual dose. Many sources of radiation Natural: radon, cosmic rays, rocks Artificial: X rays, nuclear medicine, consumer products Earth constantly bombarded by cosmic rays which produce both primary and secondary radiation. Atmosphere (plus Earth s magnetic field) provide excellent radiation shield. What if you have less atmosphere to shield you? You get more radiation airplane employees, astronauts Our skin is also a good radiation shield. Alpha and most beta particles stopped by skin, only do damage if ingested. 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 28
Radiation therapy Take advantage of cancer cells dividing quickly. Small particle accelerator produces narrow beam of x rays. 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 29
Proton therapy Less common, more complicated & expensive But can be effective for deep tissue cancer 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 30
A bigger accelerator 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 31
Other radiation applications Accelerator based radiation used for: Computer chips (iphone, PC) Car tires Diapers Shrink wrap (meat packaging) Furniture finish Other ideas under development Safe nuclear reactors (ADS) Stronger concrete All safe! No residual radioactivity. More than 30,000 accelerators in use worldwide, producing radiation for applications. 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 32
Conclusion Radiation is both friend and foe Different types of radiation exist Some are inherently safe (non ionizing) Some can be unsafe, although still often helpful Lots of things to be concerned about, radiation should not be high on your list. 7 Oct 2017 Saturday Physics Kevin Pitts (kpitts@illinois.edu) 33