The Chasman–Green lattice, also known as a double bend achromat lattice (DBA lattice), is a special periodic arrangement

Lattice (group)

In mathematics, especially in geometry and group theory, a lattice in Rn is a discrete subgroup of Rn which spans the real vector space Rn. Every lattice in Rn can be generated from a basis for the vector space by forming all linear combinations with integer coefficients...

 of magnet

Magnet

A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.A permanent magnet is an object...

s designed by Renate Chasman

Renate Chasman

Renate Wiener Chasman was a physicist.She was born Renate Wiener to German Jewish parents in Berlin. Her father, Hans Wiener, was a founder of the Social Democratic Party of Germany...

 and G. Kenneth Green of Brookhaven National Laboratory

Brookhaven National Laboratory

Brookhaven National Laboratory , is a United States national laboratory located in Upton, New York on Long Island, and was formally established in 1947 at the site of Camp Upton, a former U.S. Army base...

 in the mid 1970s. These lattices provide optimized bending and focusing of electrons in particle accelerator

Particle accelerator

A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...

 rings known as synchrotron light sources. An electron storage ring constructed with a Chasman–Green lattice has the important property that the circulating electron beam

Charged particle beam

A charged particle beam is a spatially localized group of electrically charged particles that have approximately the same velocity . The kinetic energies of the particles are typically measured in keV or MeV, much larger than the energies of particles at ambient temperature...

s have very low emittance

Beam emittance

The beam emittance of a particle accelerator is the extent occupied by the particles of the beam in space and momentum phase space as it travels. A low emittance particle beam is a beam where the particles are confined to a small distance and have nearly the same momentum...

, which results in the emission of synchrotron light

Synchrotron radiation

The electromagnetic radiation emitted when charged particles are accelerated radially is called synchrotron radiation. It is produced in synchrotrons using bending magnets, undulators and/or wigglers...

 of exceptional brightness. For this reason it is the lattice of choice for most of the premier synchrotron light source facilities worldwide.

Each period of the Chasman–Green lattice contains a focusing quadrupole magnet

Quadrupole magnet

Quadrupole magnets consist of groups of four magnets laid out so that in the multipole expansion of the field the dipole terms cancel and where the lowest significant terms in the field equations are quadrupole. Quadrupole magnets are useful as they create a magnetic field whose magnitude grows...

 symmetrically located between a pair of identical dipole magnet

Dipole magnet

A dipole magnet, in particle accelerators, is a magnet constructed to create a homogeneous magnetic field over some distance. Particle motion in that field will be circular in a plane perpendicular to the field and collinear to the direction of particle motion and free in the direction orthogonal...

s, which transports incident electrons through a bending arc to an exit path that is independent of the electron energy.