The Low Energy Ion Ring (LEIR) is a particle accelerator at

CERN The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in a northwestern suburb of Gene ...

used to accelerate ions from the

LINAC 3 The CERN hadron Linacs are Linear particle accelerator, linear accelerators that accelerate beams of hadrons from a standstill to be used by the larger circular accelerators at the facility. File:Linac1 facility at CERN.jpg, The first CERN Lina ...

to the

Proton Synchrotron The Proton Synchrotron (PS, sometimes also referred to as CPS) is a particle accelerator at CERN. It is CERN's first synchrotron, beginning its operation in 1959. For a brief period the PS was the world's highest energy particle accelerator. It ...

(PS) to provide

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

s for collisions within the

Large Hadron Collider The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundred ...

(LHC).

History

LEIR was converted from a previous machine, the

Low Energy Antiproton Ring The Low Energy Anti-Proton Ring (LEAR) was a particle accelerator at CERN which operated from 1982 until 1996. The ring was designed to decelerate and store antiprotons, to study the properties of antimatter and to create atoms of antihydrogen. ...

(LEAR), a facility to decelerate and store

antiprotons The antiproton, , (pronounced ''p-bar'') is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived, since any collision with a proton will cause both particles to be annihilated in a burst of energy. The exis ...

and to deliver them to experiments; the last LEAR antiproton run took place in 1996. LEIR was first proposed in 1993 but it wasn't until 2003 that work to transform the old experiment into the new accelerator was started. The upgrade took just over two years, being commissioned in October 2005 and tested for 4 months. In Autumn 2006 it was used to re-commission the PS to handle ions, and then again a year later it was used to re-commission the

SPS SPS may refer to: Law and government * Agreement on the Application of Sanitary and Phytosanitary Measures of the WTO * NATO Science for Peace and Security * Single Payment Scheme, an EU agricultural subsidy * The Standard Procurement System, fo ...

. However, it wasn't until November 2010, five years later, that it successfully carried out its primary role to provide the lead ions to the LHC for its first ion collisions. During 2017, LEIR was running with

xenon Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

ions, sending them normally to SPS and, exceptionally to the LHC for one day of physics. In 2018, the machine was running again with

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...

ions and had the objective to reach an LIU performance of more than charges extracted. On 6 June 2018 that performance was achieved and also a new extraction record of charges was accomplished.

Operation

LEIR takes long bunches of

lead-208 Lead (82Pb) has four stable isotopes: 204Pb, 206Pb, 207Pb, 208Pb. Lead-204 is entirely a primordial nuclide and is not a radiogenic nuclide. The three isotopes lead-206, lead-207, and lead-208 represent the ends of three decay chains: the uraniu ...

ions from the LINAC 3, and splits them into 4 bunches. Each bunch contains lead ions, which are accelerated from per

nucleon In physics and chemistry, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines the atom's mass number (nucleon number). Until the 1960s, nucleons were ...

to per nucleon before passing them through to the PS for storage. The most important function of LEIR is not acceleration, but

electron cooling Electron cooling is a method to shrink the emittance (size, divergence, and energy spread) of a charged particle beam without removing particles from the beam. Since the number of particles remains unchanged and the space coordinates and their der ...

to reduce the emittance of the ion beam in order to maintain high

luminosity Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...

of the final LHC beam. Each group of two bunches takes about 2.5 seconds to accelerate and cool, so with the LHC using 592 bunches of ions, it takes around 10 minutes for a complete fill of the LHC for operations.

References

External links

* CERN accelerators Particle accelerators {{accelerator-stub CERN facilities CERN Particle physics facilities