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  2. Alpha particle - Wikipedia

    en.wikipedia.org/wiki/Alpha_particle

    Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. [ 5 ] They are generally produced in the process of alpha decay but may also be produced in other ways. Alpha particles are named after the first letter in the Greek alphabet, α.

  3. Rutherford scattering experiments - Wikipedia

    en.wikipedia.org/wiki/Rutherford_scattering...

    Alpha particles are so tiny as to be individually invisible, but Rutherford knew from work by J S Townsend in 1902 that alpha particles ionize air molecules, and if the air is within a strong electric field, each ion will produce a cascade of ions giving a pulse of electric current. On this principle, Rutherford and Geiger designed a simple ...

  4. Radiation - Wikipedia

    en.wikipedia.org/wiki/Radiation

    Radiation, in general, exists throughout nature, such as in light and sound. In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. [1][2] This includes: electromagnetic radiation consists of photons, such as visible radiation.

  5. Ionizing radiation - Wikipedia

    en.wikipedia.org/wiki/Ionizing_radiation

    Alpha particle emissions are generally produced in the process of alpha decay. Alpha particles are a strongly ionizing form of radiation, but when emitted by radioactive decay they have low penetration power and can be absorbed by a few centimeters of air, or by the top layer of human

  6. Stopping power (particle radiation) - Wikipedia

    en.wikipedia.org/wiki/Stopping_power_(particle...

    The stopping power of the material is numerically equal to the loss of energy E per unit path length, x: = / The minus sign makes S positive. Bragg curve of 5.49 MeV alpha particles in air. The force usually increases toward the end of range and reaches a maximum, the Bragg peak, shortly before the energy drops to zero.

  7. Alpha decay - Wikipedia

    en.wikipedia.org/wiki/Alpha_decay

    v. t. e. Alpha decay or α-decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (helium nucleus) and thereby transforms or "decays" into a different atomic nucleus, with a mass number that is reduced by four and an atomic number that is reduced by two. An alpha particle is identical to the nucleus of a helium ...

  8. Radioactive decay - Wikipedia

    en.wikipedia.org/wiki/Radioactive_decay

    Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common types of decay are alpha, beta, and gamma decay.

  9. Electromagnetic radiation - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_radiation

    The basic structure of matter involves charged particles bound together. When electromagnetic radiation impinges on matter, it causes the charged particles to oscillate and gain energy. The ultimate fate of this energy depends on the context. It could be immediately re-radiated and appear as scattered, reflected, or transmitted radiation.