radioactivity presentation
DESCRIPTION
By this presentation you can get an idea about the radioactivity ; and examples will help u to understand the topic.TRANSCRIPT
Radioactive decay transforms a nucleus by emitting different particles.
• ALPHA DECAY• BETA DECAY• GAMMA DECAY
Radioactivity
Beta DecayIn BETA decay, the nucleus either emits an electron and antineutrino (or a positron and neutrino) or Captures an atomic electron and emits a neutrino.
(Note: Both alpha and beta decays change the original nucleus into the nucleus of different chemical element.)
Gamma DecayIn GAMMA decay, the nucleus lowers its internal energy by emitting a photon- a gamma ray. This decay does not modify the chemical properties of the atom.
Nuclear Chain ReactionThe principle of chain reaction is very easy therefore: a U235 nucleus is hit by a neutron, upon which fission occurs at a high probability. The neutrons produced in this process can cause more fission; moreover, the already mentioned 200 MeV energy is released each time.
The neutronic state can be characterized by the so called multiplication factor (k). This is the ratio of the number of neutrons in a neutron "generation" and the number of neutrons in the preceding generation.
APPLICATIONS Radioactive Dating Space Exploration Nuclear Reactors Smoke Detectors Nuclear Medicines Magnetic Resonance Imaging
Radioactive DatingNaturally occurring radioactive isotopes such as 14C6 are used to date objects that were living once, such as wood. For example, from the study of artifacts found at the site, scientist determined that Stonehenge was built nearly 4000 years ago.
Space ExplorationSojourner used Alpha particles to identify chemical elements present in Martian rocks. On earth nuclear reactions are used in many areas from criminal investigations to art authentication.
Nuclear ReactorsNuclear reactors use the fission of U235 or Pu239 nuclei to produce electrical power. Reactors and most other nuclear applications generate radioactive waste; disposal of this waste is a subject current research.
Smoke DetectorsMany smoke detectors use a small mount of the alpha emitter Am241 to ionize the air. Smoke entering the detector reduces the current and sets off the alarm.
Nuclear MedicineRadioactive isotopes such as Co60 and I131 are commonly use in the diagnosis and treatment of diseases. Positron emitters such as F18 are used in positron emission terminology (PET) to generate images of brain activity.