History of radioactivity презентация
Содержание
- 2. Antoine Henri Becquerel (1852-1908)
- 3. Henri Becquerel was born into a family of scientists. His grandfather
- 4. And so, upon learning how Wilhelm Roentgen discovered x-rays from the
- 5. The material Becquerel chose to work with was potassium uranyl sulphate,
- 6. Becquerel concluded “that the phosphorescence substance in question emits radiation which
- 8. Further investigation, on the 26th and 27th of February, was delayed
- 9. On the first of March, he developed the photographic plates expecting
- 10. This meant that the uranium emitted radiation without an external source
- 11. Later, Becquerel demonstrated that the radiation emitted by uranium shared certain
- 12. Pierre Curie (1859-1906) Marie Curie (1867-1934)
- 13. Pierre Curie and Marie Curie began investigating the phenomenon of radioactivity
- 14. She concluded that the ore contained, in addition to uranium, new
- 15. For their work on radioactivity, the Curies were awarded the 1903
- 16. Pierre’s teaching position at the Sorbonne was given to Marie. Never
- 17. Ernest Rutherford (1871-1937)
- 18. Ernest Rutherford is considered the father of nuclear physics. Indeed, it
- 19. Even the neutron, discovered by James Chadwick, owes its name to
- 20. For this work, Rutherford won the 1908 Nobel Prize in chemistry.
- 21. From this simple observation, Rutherford concluded that the atom’s mass must
- 22. In 1919, Rutherford returned to Cambridge to become director of the
- 23. It was here that he made his final major achievement, the
- 24. What is ionizing radiation? Ionizing radiation is radiation that has
- 25. One source of radiation is the nuclei of unstable atoms. For
- 26. Unstable isotopes of radium, radon, uranium, and thorium, for example, exist
- 27. Types of ionizing radiation alpha particle radiation
- 28. Alpha Particle Radiation An alpha particle consists of two neutrons and
- 29. The a-rays are positively charged. Because alpha particles are charged and
- 30. Alpha particles are easily shielded against and can be stopped by
- 31. However, due to the very large number of ionizations they produce
- 32. Beta Particle Radiation A beta particle is an electron emitted from
- 33. Beta particles are much less massive and less charged than alpha
- 34. Some energetic beta particles, such as those from P-32 (phosphorus), will
- 35. All beta emitters, depending on the amount present, can pose a
- 36. Gamma Ray Radiation A gamma ray is a packet (or photon)
- 37. Gamma rays are identical in nature to other electromagnetic radiations such
- 38. Like all forms of electromagnetic radiation, gamma rays have no mass
- 39. Gamma radiation is typically shielded using very dense materials (the denser
- 40. X-Ray Radiation Like a gamma ray, an x-ray is a
- 41. X-rays are produced as the result of changes in the positions
- 42. X-rays can be produced during the process of radioactive decay or
- 43. As electrons collide with this material, some have their paths deflected
- 44. Like gamma rays, x-rays are typically shielded using very dense materials
- 45. Non-ionizing Radiation Nonionizing radiations are not energetic enough to ionize
- 46. Examples of nonionizing radiation include: Examples of nonionizing radiation include: Microwaves
- 47. Natural radioactivity Definition: it is defined as the radioactivity displayed by
- 48. Artificial radioactivity Definition: artificial radioactivity is defined as the process
- 49. Fredric and Irene Curie shared the 1935 Nobel Prize in chemistry
- 50. Natural background radiation To put these radiation effects into perspective,
- 51. By natural radiations, we mean those radiations within the environment over
- 52. For example, cosmic radiations bombard the earth from outer space and
- 53. Our exposure to cosmic radiation will therefore depend on the altitude
- 54. The major source of “natural” radiation is the gas radon. Radon
- 55. Atom
- 56. Atom model of the hydrogen
- 57. Atom model There are three parts of
- 58. Nuclei are referred to using the following Nuclei are
- 59. Z is the atomic number. It characterizes the element. It also
- 60. A is called the “mass number” and is equal to the
- 61. A species of nucleus of given Z and A is called
- 62. The proton is the part of an atom that helps to
- 63. A neutron is the part of an atom that holds no
- 64. Electrons are the smallest parts of the atom and have a
- 65. The positron is identical to the electron except that it carries
- 66. Radioactive decay
- 67. Radioactive decay is the process in which an unstable atomic nucleus
- 68. For example: a carbon-14 atom (the “parent”) emits radiation and transforms
- 69. The SI (international system) unit of activity is the bequerel (Bq).
- 70. Half-life Half-life is the period of time it takes for a
- 71. For example: consider 10 kg of radioelement with a half-life of
- 72. Initially, the rate of disintegration is rapid, but it becomes slower
- 73. Therefore, for comparison between different radioactive substances we consider the quantity
- 74. Radiation protection principle There are four basic radiation protection principles that
- 75. Time Time is an important factor in radiation protection. The principles
- 76. Many radiation monitoring devices measure exposure in milliroentgens (mR) per hour.
- 77. Distance The second radiation protection factor is distance, and the principle
- 78. For example, a source of radiation that measures 8 mR/hr at
- 79. Shielding The third radiation protection factor is shielding. The principle follows
- 80. In addition, some specialty centers for radiation accident management have constructed
- 81. In emergency management of the contaminated patient, shielding is limited to
- 82. However, it does not stop penetrating gamma radiation. In the hospital
- 83. Quantity The fourth radiation protection factor is quantity. Because the exposure
- 84. At work with the closed sources of radiations there is a
- 85. Check of tightness of the closed sources is necessary for carrying
- 86. At work with the closed sources of the mall sizes there
- 87. Скачать презентацию
Слайды и текст этой презентации