1 / 32

Radioactivity

Radioactivity . Basic Principles and Effects on the Human Body. Table of Contents. 1. Basic Principles of Radioactivity 1.1 Alpha rays 1.2 Beta+- and beta- rays 1.3 Gamma rays. 2. Experiments on Radiation 2.1 Experiment 1: Measuring the radioactivity of Co-60

justin
Download Presentation

Radioactivity

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Radioactivity Basic Principles and Effects on the Human Body

  2. Table of Contents • 1. Basic Principles of Radioactivity • 1.1 Alpha rays • 1.2 Beta+- and beta- rays • 1.3 Gamma rays • 2. Experiments on Radiation • 2.1 Experiment 1: Measuring the radioactivity of Co-60 • 2.2 Experiment 2: Effective penetration of Co-60 • 3. Effects of Radioactive Radiation • 3.1 The radioactive catastrophe in Chernobyl • 3.2 Effects on the human body • 3.3 Long-term results caused by radiation • 3.4 Medical advances

  3. Basic Principles of Radiation

  4. 1. Basic Principles of Radiation • the most well-known type of radiation is nuclear fission • when fission takes place two heavy atom nuclei fractionalise • the energy that is released causes the fragments to fly apartat great speed • a heavy atom nucleus can fractionalise by emitting -rays(-radiation) • an unfavourable ratio between protons and neutrons can be compensated when beta- or beta+ rays are emitted • through this fission the resulting nucleus is more stable than the original atom nucleus

  5. 1. Basic Principles of Radiation 1.1 Alpha Rays • Special radionuclides (- emitters) emit helium nuclei • These helium nucleii comprise 2 protons and 2 neutrons • They reach a speed of around 15 000 km/h • Their decay often leads to the productin of gamma-rays • - rays give off all their energy after they have flownonlya few centimetres

  6. 1. Basic Principles of Radiation 1.2 Beta+- und Beta- Rays • When beta-radiation takes place a neutron is transformed into a proton when an electron is split • A new element is then formed, in this case Cs-137 becomes Ba-137 • Depending on their strength beta rays are able to penetrate thin layers and cause damage to the human body

  7. 1. Basic Principles of Radiation 1.2 Beta+- and Beta- Rays • When beta+ radiation occurs a neutron is transformed into a proton when a positively charged electron (positron) is split • A new element is formed, in this case Na-22 becomes Ne-22

  8. 1. Basic Principles of Radiation 1.3 Gamma Radiation • discovered by Wilhelm Conrad Röntgen • like visible light it is electromagnetic but contains more energy • produced by nuclear transformation (alpha or beta decay) • is emitted in the form of gamma quanta • these quanta move at a speed of 300 000 km/s (speed of light) • its wave length (frequency) measures 0.5 nm • can also penetrate very dense materials such as lead

  9. 1. Basic Principles of Radiation 1.3 Gamma Rays • A great amount of energy is set free when alpha and beta rays fractionalise • During nucleus transformation the nucleus changes from a low state to a stable state

  10. Experiments on Radioactivity

  11. 2. Experiments on Radioactivity 2.1 Experiment 1: Measuring the Radioactivity of 60 cobalts To determine the intensity of a Co-60 emitter the Becquerel values (impulse/time) are measured with a Geiger counter at different distances. Video 1

  12. Video 1 :

  13. Co-60 16

  14. Co-60 16 4

  15. Co-60 16 4 2

  16. 2. Versuche zur Radioaktivität 2.1 Experiment 1: Experiment to demonstrate quadratic fall in gamma rays Evaluation - In this experiment the impulses per unit of time (Becquerel = Impulse/time) for the gamma rays are measured at particular distances. - It was noted that the longer the distance (5cm; 10cm; 20cm; 30cm and 40 cm) the more the intensity of the gamma rays fell. A Geiger counter showed that this fall is a quadratic reduction. - This observation is explained through the 1/r2 law.

  17. 2. Experiments on Radioactivity 2.2 Experiment 2: Effective penetration of 60 cobalts To determine the surface density of materials, these are bombarded with Co-60 rays. The emitted - rays are measured using a Geiger counter. Video 2

  18. Video 2 :

  19. 2. Versuche zur Radioaktivität 2.2 Experiment 2: Effective penetration of Co-60 Evaluation - For this experiment the impulses per unit of time (Becquerel) for gamma rays are measured that are shielded by a particular material. - It was noted that different materials (Plexiglas, aluminium, lead and cement) deflect or absorb the gamma rays due to the varying properties of transmission, reflection and absorption. - This method is suitable to determine the thickness of certain layers of known materials.

  20. Co-60

  21. Effects of Radioactive Radiation

  22. 3. Effects of Radioactive Radiation 3.1 Radioactive catastrophe of Chernobyl -26th April 1986: Catastrophe of the century - Source of this catastrophe: Serious operating errors, deactivated safety systems -The catastrophe was triggered when an incorrect experiment was carried out in Reactor 4 of the nuclear power plant

  23. 3. Effects of Radioactive Radiation 3.1 Radioactive Catastrophe in Chernobyl -Enormous amounts ofI-131 and Cs-137 (radioactivity, formation of dangerous aerosols) were emitted into the atmosphere - these dangerous aerosols were carried hundreds of kilometres

  24. 3. Effects of Radioactive Radiation 3.1 The Radioactive Catastrophe in Chernobyl • Result of this catastrophe: 203 people were immediately taken to hospital, of these 31 died • The surrounding area had to be evacuated at once and 135,00 people had to move to new homes - The radioactive cloud comprising I-131 and Cs-137 also reached Western Europe causing the soil there to be contaminated with radioactive substances - In 1987: The number of people suffering from cancer rose as a result of the catastrophe in Chernobyl

  25. 3. Effects of Radioactive Radiation 3.2 Effects on the human body • 0,3 mSv/a • Limit for an effective dose of radioactive discharge to the population through water and air • 2,0 mSv/a • medical radiation • < 3 mSv/a • natural radiation when living in a cement or granite building 250 mSv - first clinical measurable effects of radiation when a patient has one session of radiation to his/her whole body

  26. 3. Effects of Radioactive Radiation 3.2 Effects on the human body • ca. 1000 mSv • - temporary radiation sickness, one-off radiation of whole body ca. 4000 mSv - serious radiation sickness, 50 % mortality rate if victim remains untreated, one-off radiation of whole body • ca. 7000 mSv • fatal dose, no medical treatment, one-off radiation of whole body

  27. 3. Effects of Radioactive Radiation 3.3 Long-term Effects of Radiation - Liquidator committee: 100,000 cleaning staff died from long-term effects - 31official fatalities from international organisations - 1,800 children became ill with cancer of the thyroid - UNICEF and UNDP: In the years after the accident in Chernobyl the number of cases of illness among children any adolescents rose to 8000 (Status: January 2002)

  28. 3. Effects of Radioactive Radiation 3.3 Long-term effects of radiation - Long-term consequence: Number of cases of breast cancer doubled - Ukrainian scientists state: Rise in the number of tumour illnesses relating to urinary tract, reproductive organs, lungs and colon • According to the UNDP and UNICEF the causes for this are: Poverty, poor nutrition, unhealthy environment and psychological • consequences -Result: Number of cases of sickness are higher in contaminated areas than in uncontaminated regions

  29. 3. Effects of Radioactive Radiation 3.4 Medical Advances Radiation Therapy to Treat Brain Tumours • there are different types of radiation treatment, external radiation treatment is the most widely used • the radiation dose is measured in Gray (GIy) • during each session of radiation treatment the patient receives a small individual dose of approximately 1.8 to 2.0 Gly - radiation treatment works by using ionising rays to damage fast growing cells - nowadays one uses protons or, more recently, heavy ions to treat brain tumours because these can damage deep-seated tumours

  30. 3. Effects of Radioactive Radiation 3.4 Medical Advances Radiation with fast Neutrons • in addition to x-rays fast (highly energy) neutrons will be used in future to kill tumour cells • neutrons (particle radiation) can damage slightly more tumour cells than x-rays - damaged cells cannot regenerate completely and the tumour cell is destroyed

  31. Radioactivity A presentation by: - Daniel Demecz - Kevin Grundke - Mira Arnold - Agnes Schimitzek - (Corinna Engelhardt) Any questions ?

  32. THE END

More Related