Femtometre

The femtometre (American spelling femtometer, symbol fmAncient Greek: μέτρον, metrοn, "unit of measurement") is an SI unit of length equal to 10−15metres. This distance can also be called fermi and was so named in honour of physicist Enrico Fermi, as it is a typical length-scale of nuclear physics.

Definition and equivalents

1000 attometres = 1 femtometre = 1 fermi = 0.001 picometre = 1.0 × 10−15metres

1,000,000 femtometres = 10 Ångström = 1 nanometre.

For example, the charge radius of a proton is approximately 0.84–0.87 femtometres while the radius of a gold nucleus is approximately 8.45 femtometres.

1 barn = 100 fm2

History

The femtometre was adopted by the 11th Conférence Générale des Poids et Mesures, and added to SI in 1964.

The fermi is named after the Italian physicist Enrico Fermi (1901–1954), one of the founders of nuclear physics. The term was coined by Robert Hofstadter in a 1956 paper published in Reviews of Modern Physics entitled "Electron Scattering and Nuclear Structure". The term is widely used by nuclear and particle physicists. When Hofstadter was awarded the 1961 Nobel Prize in Physics, it subsequently appears in the text of his 1961 Nobel Lecture, "The electron-scattering method and its application to the structure of nuclei and nucleons" (December 11, 1961).

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This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Femtometre

Distances shorter than 1 pm

This page lists lengths shorter than 1 picometre (10−12 m).

Femtometre scale

  • 1 × 10−13 metres = 100 fm = 0.1 pm.
  • ≈ 1 × 10−13 metres = 1 x unit
  • 1 × 10−14 metres = 10 fm
  • 7 fm - the radius of the effective scattering cross section for a gold nucleus scattering a 6 MeV alpha particle over 140 degrees
  • 2.81794 fm — classical electron radius
  • 1.5 fm — diameter of the Scattering Cross Section of an 11 MeV proton with a target proton
  • 1 × 10−15 metres = 1 fm = 1 femtometre = 1,000 attometres

    • Attometre scale

  • 850 am = 0.85 fm — approximate proton radius
  • 1 × 10−16 metres = 100 am
  • 1 × 10−17 metres = 10 am
  • 1 × 10−18 metres = 1 am = 1 attometre = 1,000 zeptometres
  • 1.0 am — sensitivity of the LIGO detector for gravitational waves.

    • Zeptometre scale

  • 310 zm — de Broglie wavelength of protons at the Large Hadron Collider (4 TeV as of 2012)
  • 1 × 10−19 metres = 100 zm
  • 1 × 10−20 metres = 10 zm
  • 7 × 10−21 metres = radius of effective cross section for a 250 GeV neutrino scattering off a nucleon
    • Read more
    This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Distances_shorter_than_1_pm

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