Radiation

Examples of Radiation in the following topics:

• Therapeutic Uses of Radiation

  • Radiation therapy uses ionizing radiation to treat conditions such as hyperthyroidism, cancer, and blood disorders.
  • Radiation therapy involves the application of ionizing radiation to treat conditions such as hyperthyroidism, thyroid cancer, and blood disorders.
  • Ionizing radiation works by damaging the DNA of exposed tissue, leading to cellular death.
  • Radiation therapy is in itself painless.
  • Radiation therapy of the pelvis.

• Medical Imaging and Diagnostics

  • Radiation therapy uses ionizing radiation to treat conditions such as hyperthyroidism, cancer, and blood disorders.
  • Radiation therapy involves the application of ionizing radiation to treat conditions such as hyperthyroidism, thyroid cancer, and blood disorders.
  • Ionizing radiation works by damaging the DNA of exposed tissue, leading to cellular death.
  • Radiation therapy is in itself painless.
  • Radiation therapy of the pelvis.

• Planck's Quantum Hypothesis and Black Body Radiation

  • A black body emits radiation called black body radiation.
  • Planck described the radiation by assuming that radiation was emitted in quanta.
  • A black body in thermal equilibrium (i.e. at a constant temperature) emits electromagnetic radiation called black body radiation.
  • Max Planck, in 1901, accurately described the radiation by assuming that electromagnetic radiation was emitted in discrete packets (or quanta).
  • Contrary to the common belief that electromagnetic radiation can take continuous values of energy, Planck introduced a radical concept that electromagnetic radiation was emitted in discrete packets (or quanta) of energy.

• Radiation

  • In these examples, heat is transferred by radiation.
  • There is a clever relation between the temperature of an ideal radiator and the wavelength at which it emits the most radiation.
  • The rate of heat transfer by emitted radiation is determined by the Stefan-Boltzmann law of radiation:
  • If you knock apart the coals of a fire, there is a noticeable increase in radiation due to an increase in radiating surface area.
  • A black object is a good absorber and a good radiator, while a white (or silver) object is a poor absorber and a poor radiator.

• Biological Effects of Radiation

  • Ionizing radiation is generally harmful, even potentially lethal, to living organisms.
  • Ionizing radiation is generally harmful, even potentially lethal, to living organisms.
  • Although radiation was discovered in the late 19th century, the dangers of radioactivity and of radiation were not immediately recognized.
  • Other conditions, such as radiation burns, acute radiation syndrome, chronic radiation syndrome, and radiation-induced thyroiditis are deterministic, meaning they reliably occur above a threshold dose and their severity increases with dose.
  • Two pathways of exposure to ionizing radiation exist.

• Radiation Detection

  • A radiation detector is a device used to detect, track, or identify high-energy particles.
  • A radiation detector is a device used to detect, track, or identify high-energy particles, such as those produced by nuclear decay, cosmic radiation, and reactions in a particle accelerator.
  • Modern detectors are also used as calorimeters to measure the energy of detected radiation.
  • Gaseous ionization detectors use the ionizing effect of radiation upon gas-filled sensors.
  • Scintillators are used by the American government, particularly Homeland Security, as radiation detectors.

• A Physical Aside: Multipole Radiation

  • It is possible to calculate the radiation field to higher order in $L/(c\tau)$.This is necessary if the dipole moment vanishes, for example.
  • where $k\equiv\omega/c$$n=0$ gives the dipole radiation, $n=1$ gives the quadrupole radiation and so on.

• A Physical Aside: Intensity and Flux

  • Blackbody radiation is a radiation field that is in thermal equilibrium with itself.
  • In general we will find it convenient to think about radiation that is in equilibrium with some material or its enclosure.
  • Using detailed balance between two enclosures in equilibrium with each other and the enclosed radiation we can quickly derive several important properties of blackbody radiation.
  • The intensity ($I_\nu$) of blackbody radiation does not depend on the shape, size or contents of the enclosure.

• Introduction

  • We are going to set the stage for a deeper look at astrophysical sources of radiation by defining the important concepts of radiative transfer, thermal radiation and radiative diffusion.
  • One can make a large amount of progress by realizing that the distances that radiation typically travels between emission and detection or scattering etc. are much longer than the wavelength of the radiation.

• Infrared Waves

  • Infrared (IR) light is EM radiation with wavelengths longer than those of visible light from 0.74 µm to 1 mm (300 GHz to 1 THz).
  • Mid-infrared, from 30 to 120 THz (10 to 2.5 μm) - Hot objects (black-body radiators) can radiate strongly in this range, and human skin at normal body temperature radiates strongly at the lower end of this region.
  • Infrared radiation is popularly known as "heat radiation," but light and electromagnetic waves of any frequency will heat surfaces that absorb them.
  • Many astronomical objects emit detectable amounts of IR radiation at non-thermal wavelengths.
  • Infrared radiation can be used to remotely determine the temperature of objects (if the emissivity is known).