Participants: Sergio, Guillaume, Alban, Giovanni, Damiano, Sarah, Giovanna, Erk, Tobi
1. Review Legnaro workshop
2. TTC High Q0 working group. Review of last meeting and CERN strategy for further meetings.
How should we contribute and coordinate
- Sarah gave a presentation reviewing these two events.
- It was decided to coat a Qudrupole Resonator (QPR) bulk niobium sample with a standard
dcms film. Tobi will calculate the optimal layer thickness based on the penetration depth
measurements from RF and muon spin rotation. Sarah will look for a suitable sample
- Sarah will contact Yulia from Fermilab to perform TEM measurements at cryogenic
temperatures of niobium on copper samples next year
- Sarah proposed to investigate rather NbTiN than Nb3Sn. Advantages: Less brittle, no
diffusion of copper and metallic. Sergio argued that there are different problems with NbTiN
(high temperature required, reactive sputtering is difficult if the surface ration between
cathode and target is large). Sergio will distribute a thesis on NbTiN
- Sergio reported that a Nb3Sn cathode has already been ordered. In situ annealing needs to
be investigated.
- There was consent that investigating deposition at higher temperatures should be a major
effort in the near future.
- The possibility of nitrogen doping of niobium films was discussed.
- The problem is to create a layer which the right amount of nitride that does not require
etching .
- Giovanna proposed to investigate low pressure and long time treatments
- Alban proposed to use the Isolde sputtering configuration to produce N doped samples for
the QPR
- Erk volunteered Sarah to create an international working group for thin films. In the next
meeting it will be discussed which participants will be invited and whether it is useful to
create this group as a TTC working group.
3. Latest results from 150⁰C baked HIPIMS cavity
-Tobi gave a presentation on latest results since the thin film workshop
-Giovanna proposed to perform direct thermal/Kapitza resistance measurements in the
cryolab to directly confirm Tobi’s conclusion that a global warming of the inner cavity
surface is not the reason for the Q-slope of niobium on copper cavities
-Measurements of M.2.7 will be finished by penetration depth measurements
4. Future plans and planning for QPR and 1.3 GHz cavities
- It was decided to test until the end of the year one dcms cavity on M.2 substrate for
comparison HIPIMS to dcms (milestone for Giovanni’s thesis)
- After the first cold test the input antenna will be exchanged by a crooked one to measure
the cavity in the TE011 mode (no surface electric fields)
- It was decided to do a HIPIMS coating on a QPR sample for comparison ECR and HIPIMS
(milestone for Sarah’s thesis)
5. Publication of muSR and PCT results
- Discussion was after the meeting between Sergio and Tobi. It was decided to publish PCT
and muSR in two SFR proceeding papers
- It was decided to publish cavity results in a Journal
6.
7.
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Fate of the KEK cavity
Measurement foreseen for beginning of next year
Sarah and Tobi will provide a list of missing items
Masterplan to reveal the origin of the Q-slope of sputter coated cavities (all)
The meeting was finished by a small open discussion. It was decided to have bi-weekly
meetings organised by Tobi until the end of the year and then by Sarah