quadrupole

physics

Also known as: electric quadrupole

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July 13, 2026

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A quadrupole is a system made up of two dipoles with equal but opposite moments. In particle accelerators, quadrupole magnets are used to focus particle beams, keeping them narrow and intense. These magnets have four poles, two north and two south, arranged opposite each other. This setup directs particles toward the center in one direction while allowing them to spread in the perpendicular direction.12

Quadrupole moments are also relevant in nuclear structure, measuring deviations from sphericity in the charge distribution of a nucleus. In the context of gamma transitions in radioactivity, electric quadrupole (E2) and magnetic quadrupole (M2) transitions involve a change of two units of angular momentum carried off by the radiation.34

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magnetic resonance
Nuclear magnetic resonance
…electric quadrupole moments (an electric quadrupole consists of a charge distribution equivalent to a special arrangement of two electric dipoles) that interact with the electric fields that exist at the nuclear sites. These interactions provide information on the microscopic distribution of electric charge around the nucleus.
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…electric quadrupole moments (an electric quadrupole consists of a charge distribution equivalent to a special arrangement of two electric dipoles) that interact with the electric fields that exist at the nuclear sites. These interactions provide information on the microscopic distribution of electric charge around the nucleus.
Read More

radioactivity
Gamma transition
…change, the transition is electric quadrupole (E2), analogous to a full-wave linear antenna of two dipoles out-of-phase, and magnetic quadrupole (M2), analogous to coaxial loop antennas driven out-of-phase. Higher multipolarity radiation also frequently occurs with radioactivity.
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…change, the transition is electric quadrupole (E2), analogous to a full-wave linear antenna of two dipoles out-of-phase, and magnetic quadrupole (M2), analogous to coaxial loop antennas driven out-of-phase. Higher multipolarity radiation also frequently occurs with radioactivity.
Read More

particle accelerator
Guiding particles
…of focusing magnet is a quadrupole, a magnet built with four poles (two norths and two souths) arranged opposite each other. This arrangement pushes particles toward the centre in one direction but allows them to spread in the perpendicular direction. A quadrupole designed to focus a beam horizontally, therefore, will…
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…of focusing magnet is a quadrupole, a magnet built with four poles (two norths and two souths) arranged opposite each other. This arrangement pushes particles toward the centre in one direction but allows them to spread in the perpendicular direction. A quadrupole designed to focus a beam horizontally, therefore, will…
Read More