12 GeV Developments

JLab is continuing work on the 12 GeV upgrade of CEBAF. The CEBAF@12GeV website describes the overall project and its physics motivations. Below are some highlights of our current prototype cryomodule for the upgrade. We call it Renascence.

  • Latest Jefferson Lab cryomodule design
    • Optimized for CW use in CEBAF
    • Prototype for the CEBAF 12 GeV Upgrade
    • Need >108 MV with 250 W dynamic heat load at 2 K
  • Uses eight 7-cell 1497 MHz niobium cavities
    • Mixture of two differently-optimized cell shapes
      • “HG” optimized for minimum peak surface electric fields
      • “LL” optimized for minimum cryogenic losses
    • Q 0 > 8e9 @ > 19.2 MV/m average
  • Improved power handling, HOM damping, and assembly features in cryomodule design
  • All cavities have been built at Jefferson Lab, and all have passed their qualification tests at 2 K in the JLab vertical test area
  • Assembly of the 8-cavity string is complete. Assembly of the balance of the cryomodule around the string will continue into June 2005. This string is the first JLab unit that avoids all use of indium wire seal gaskets.
  • Renascence received extensive testing in the JLab Cryomodule Test Facility and is slated for installation in CEBAF during the Fall maintenance down.
  • Progressively unwrapped Renascence cryomodule design

Cross-section of the LL cavity assembly including titanium helium vessel, tuner, and input waveguide system

  • The Renascence cavities were produced in-house at JLab following batch production procedures.
  • HG cavities have been successfully qualified for use.

  • LL cavities have performed very well and have been identified as the optimal choice for the CEBAF 12 GeV Upgrade.


  • 3D modeling codes now permit simulation of complex rf structure geometries so that localized field enhancements which might limit performance can be identified and understood early.