Keyword: superconductivity
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PO10 Performance of ALPI New Medium Beta Resonators cavity, vacuum, cathode, pick-up 73
  • A.M. Porcellato, F. Chiurlotto, M. De Lazzari, A. Palmieri, V. Palmieri, S. Stark, F. Stivanello
    INFN/LNL, Legnaro (PD), Italy
  All the Nb sputtered medium beta cavities installed up to the last year in ALPI were produced by upgrading of old previously Pb plated substrates. For the first time this year we had the opportunity to test on line four 160 MHz, β=0.11 QWRs which were designed and built in order to be Nb sputtered. These resonators were sputtered in between 2007 and 2008 and they were tested at low fields (up to 3 MV/m) just after their production when they showed Q-zero values exceeding 1xE9. They were then stored for about three years in plastic bags and installed in ALPI only this year. The on line tests that we performed after installation showed Q-zero values reduced of about a factor five with respect to the ones measured in laboratory. It is the first time we could pick out a Q deterioration caused by storage in air. So far we have not recognized any Q–degradation both when the sputtered cavities were maintained in vacuum for many years and also when they were open to air for a few weeks for cryostat maintenance. In such a case, as it happened in the maintenance of cryostat CR19 housing high beta resonators, we could instead find some improvements in the Q-curves.