Electron–ion collider

An electron–ion collider (EIC) is a type of particle accelerator collider designed to collide spin-polarized beams of electrons and ions, in order to study the properties of nuclear matter in detail via deep inelastic scattering. In 2012, a whitepaper was published, proposing the developing and building of an EIC accelerator, and in 2015, the Department of Energy Nuclear Science Advisory Committee (NSAC) named the construction of an electron–ion collider one of the top priorities for the near future in nuclear physics in the United States. In 2020, The United States Department of Energy announced that an EIC will be built over the next ten years at Brookhaven National Laboratory (BNL) in Upton, New York, at an estimated cost of $1.6 to$2.6 billion. On 18 September 2020, a ribbon-cutting ceremony was held at BNL, officially launching the development and building of the EIC. In the US, Brookhaven National Laboratory has a declared design for an EIC scheduled to be built in the 2020 decade. In Europe, CERN has plans for the LHeC. There are also Chinese and Russian plans for an electron–ion collider. Brookhaven National Laboratory's conceptual design, eRHIC, proposes upgrading the existing Relativistic Heavy Ion Collider, which collides beams of light to heavy ions including polarized protons, with a polarized electron facility. On January 9, 2020, It was announced by Paul Dabbar, undersecretary of the US Department of Energy Office of Science, that the BNL eRHIC design was selected over the conceptual design put forward by Thomas Jefferson National Accelerator Facility as the design of a future EIC in the United States. In addition to the site selection, it was announced that the BNL EIC had acquired CD-0 (mission need) from the Department of Energy. The LHeC would make use of the existing LHC accelerator and add an electron accelerator to collide electrons with the hadrons. In order to allow understanding of spin dependence of the electron-nucleon collisions, both the ion beam and the electron beam must be polarized.