• T.T. Arkan, H. Carter, M.S. Champion, E.R. Harms, R.D. Kephart, J.R. Leibfritz
  Fermilab, Batavia

Fermilab has produced two cryomodules for superconducting RF (SRF) applications to date. The first of these is an ILC prototype containing eight 1.3 GHz Tesla-type cavities and a superconducting quadrupole. This cryomodule is of the 'Type 3+' design developed by the TESLA collaboration. The assembly of this cryomodule was accomplished at Fermilab with much assistance from DESY and INFN-Milano. The cryomodule was tested at Fermilab in the summer of 2010. The second cryomodule produced at Fermilab contains four 3.9 GHz nine-cell cavities. The cavities and cryomodule were designed at Fermilab; the design concepts are quite similar to the 1.3 GHz Type 3+ cryomodule. This cryomodule was shipped to DESY, tested, and is now operating as part of a third-harmonic system in the FLASH facility. Fermilab plans to build five more 1.3 GHz cryomodules over the next several years for a total of six, which will be installed and operated in the New Muon Lab beam test facility at Fermilab.

• J. Norem, M. Kharitonov, J. Klug, M.J. Pellin, Th. Proslier
  ANL, Argonne
• N. Becker, J. Zasadzinski
  IIT, Chicago, Illinois
• G. Ciovati
  JLAB, Newport News, Virginia
• A.V. Gurevich
  NHMFL, Tallahassee, Florida

An effort, centered at Argonne, has started to explore the use of Atomic Layer Deposition (ALD) to study and improve the performance of superconducting rf (SRF) accelerating structures. This effort has a number of parts: a survey the properties of ALD deposited films, a study of loss mechanisms of SRF structures, and a program of coating single cell cavities, to begin to optimize the performance of complete systems. Early results have included improving the performance of individual structures and, identification of magnetic oxides as a loss mechanism in SRF. We describe the program and summarize recent progress.