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After three years of preparation, two superstructures, each made of two superconducting 7-cell weakly coupled subunits, have been installed in the TESLA Test Facility linac (TTF) for the cold-and beam test. The energy stability, the HOMs damping, the frequency and the field adjustment methods were tested. The measured results confirmed expectation on the superstructure performance and proved that alternative layout for the 800 GeV upgrade of the TESLA collider, as it was proposed in TDR [1], is feasible. We report on the test and give here an overview of its results which are commented in more detail elsewhere in these Proceedings.

a b s t r a c tThree accelerator prototype cryomodules (CMs) for the European XFEL have been produced, assembled and tested at DESY in a wide international collaboration. The heat load budget is a key element in the qualification of these CMs. We describe in this paper the measurements performed in the Cryomodule test bench (CMTB) to evaluate the thermal performances of the three prototype CMs. We present at first the methodology and instrumentation used for the measurements, then we analyse the main contributions to the heat loads at various temperature levels and finally we compare the measured values with the ones calculated and reported in the first part of this paper.

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In the version of this Article originally published, the surname of the author N. Johansson was misspelled as 'Johannson'. In addition, in affiliation 17, "University of Łódź" was incorrect; it should have read "Łódź University of Technology". These errors have been corrected in the online versions of the Article and its Supplementary Information.