  In a partnership with SLAC National Accelerator Laboratory (SLAC) and
Jefferson Lab, Fermilab will assemble and test 17 of the 35 total 1.3 GHz
cryomodules for the Linac Coherent Light Source II (LCLS-II) Project. These
devices will be tested at Fermilab's Cryomodule Test Facility (CMTF) within the
Cryomodule Test Stand (CMTS-1) cave. The problem of magnetic pollution became
one of major issues during design stage of the LCLS-II cryomodule as the
average quality factor of the accelerating cavities is specified to be $2.7
\times 10^{10}$. One of the possible ways to mitigate the effect of stray
magnetic fields and to keep it below the goal of 5 mGauss involves the
application of low permeable materials. Initial permeability and magnetic
measurement studies regarding the use of 316L stainless steel material
indicated that cold work (machining) and heat affected zones from welding would
be acceptable.

Accelerator Physics