EIC luminosity

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CMlumi ep Aug2010.png
CMlumi eA Aug2010.png

This is a summary of machine designs for the EIC in terms of a luminosity profile as a function of the center of mass energy. The tables and plots summarize the designs as of Aug 2010 and are intended for use at the INT Fall 2010 program on EIC physics; updated information can be obtained thorugh References and Links below.

In the e+A case the energies are per nucleon and are simply scaled from the proton energy according to E_A=Z/A*E_p, and the luminosities are multiplied by the number of nucleons since we are mostly interested in hard scattering processes. Keep in mind, however, that these luminosity profiles are often based on scaling calculation and further analysis will be needed to verify these numbers. The sqrt(s) vs. luminosity plots on the right summarizes all these numbers for the e+p and e+A case respectively.

These sets of parameters, which are in many cases intertwined with the final performance in terms of luminosity, acceptance and energy range where such luminosity and acceptance are optimized, is not to be seen as the final set of EIC parameters, but is meant to give you a basis to gauge the nuclear science output of the envisioned EIC, and work towards this Fall's INT program on the science case for an EIC [1]. The parameters are expected to be adjusted later on, to optimally synchronize the design with the maximum science output, folding in the findings of our physics simulations.

JLEIC (formerly MEIC/ELIC) at JLab

The MEIC/ELIC design

The presented MEIC luminosity profile (ca. 2010) is based on a 1 km long figure eight tunnel, and a 8 mm vertical beta* for both electron and ion beams (horizontal beta-star are 5 to 15 times larger). The proton energy of 60 (96) GeV is reached with a 6T (8T) magnetic field. The ELIC luminosity is based on a 2.5 km tunnel, 8T magnetic field, and 8mm vertical beta*. The electrons are injected from CEBAF with an energy of 3-11 GeV. The highest energy of 20 GeV can be obtained by boosting the electron energy from 11 GeV (feeded from CEBAF) to 20 GeV in the ring with RF cavity, just like the proton beam. The quoted luminosities include the hourglass effect.

The staging will be done by first building MEIC, and then ELIC.

For more uo-to-date details and questions:

Older info:


The eRHIC design

The presented eRHIC design (ca. 2010) has an electron beam with energies ranging from 5 to 20 GeV (and 30GeV) with CeC (Litvinenko and Derbenev, 2009). The hadron beam energy can be varied and has it maximum at 325 GeV for protons, giving a maximum centre of mass energy of 161 GeV (200GeV). The luminosity is flat with E_e=5-20, and drops by about a factor 5 for E_e=30. It is also flat for E_p=130-325, and for smaller energies can be scaled according to L = 14.6 * E/130. The quoted luminosities include the hourglass effect. Note: For the convenience of users and INT program participants, the table contains a few more examples than in the official eRHIC luminosity page, based on the mentioned energy scaling law.

The staging of eRHIC is done in the RF of the machine, if more money is available the linacs will be extended and the lepton energy increased. All other machine elements will be there from the beginning. In stage 1, the lepton beam will likely have an energy of 5 GeV only, and the corresponding reach in energy is marked by a black vertical line in the plots. Note that in stage 2 the same c.m. energy can be obtained with more symmetric beam configurations, but at the price of a reduced luminosity. For example, e+p collisions at sqrt(s)=40 GeV can be obtained with 5+80, 10+40 or 20+20 GeV beams at luminosity of 8.98, 4.49, 2.25, respectively.

For more details and questions:

Future energy upgrade (see V.Litvinenko @ Stony Brook, Jan 2010 [3])

The RHIC magnets are more or less the SSC design but with coils removed. One could now install LHC class magnets in one of the rings and get RHIC up to 800 GeV p or 320 GeV ions. 30+800 is sqrt(s) = 310 GeV which is Hera. This would be considered an upgrade of eRHIC, and is not included in the table and summary plots.


The LHeC machine will add an electron accelrator to the existing LHC hadron collider. In the ring-ring design (shown in the plot) it will collide electrons at Ee-40-80 GeV on protons up to Ep=7 TeV, witgh L~10^33. In the linac-ring design the electron energy span will be larger, Ee=40-150, at the price of a reduction in luminosity of about a factor 2, L~0.4x10^33.


The ENC project attempts to realize an electron-nucleon collider at the upcoming Facility for Antiproton and Ion Research FAIR at GSI Darmstadt by utilizing the antiproton high-energy storage ring HESR for polarized proton and deuteron beams, with the addition of a 3.3 GeV storage ring for polarized electrons.

References and Links

  • A collection of documents in preparation of the long range planning 2015 [4]
  • The EIC science case has been explored in:
    • the QCD town meeting at Temple U., 13-15 Sep 2014, in preparation to the next Long Range Plan).
    • The EIC white paper (Dec 2012) [5]
    • The Fall 2010 INT workshop report [6]
    • A mini review by Accardi et al. (Oct 2011) [7]
    • The Summary of the Pre-Town Meeting on Spin Physics at an Electron Ion Collider, E. Aschenauer et al. (Oct 2014) [8]
  • See also the design reports:
    • JLEIC (formerly MEIC)
      • Conceptual design report, Sep 2012 [9]
      • Design summary, Jan 2015 [10]
    • eRHIC
      • Design report, Sep 2014 [11]
  • The evolution in the designs can be appreciated looking at the talks delivered at:
    • The 2016 EIC Users Group Meeting at the Argonne Laboratory, June 2016; see talks by F.Pilat and V.Pitsyn
    • the 2014 EIC collaboration meeting at Stony Brook U., June 2014. In particular,
      • the MEIC design status talk by F. Pilat [12]
      • the eRHIC design status by V. Litvinenko [13]
    • the 2010 EIC collaboration meeting at the Catholic University of America in Washington, DC, July 2010, especially:
      • the eRHIC design status talk by V.Pitsyn [14], and
      • the MEIC/ELIC design status talk by G.Krafft [15]
      • For an (old) overview and comparison of EIC designs, and comparison to the LHeC at CERN and the ENC at FAIR, see "Future electron-ion colliders," talk by V.Litvinenko at IPAC'10, Kyoto, Japan [16]
  • Up-to-date information on the LHeC machine designs can be found on the LHeC working group home-page [17]