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Weekly meeting on Xboxes
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18/3-008 - CLIC Meeting room (CERN)
Description
https://cern.zoom.us/j/6910405761
Weekly meeting on Xboxes
Zoom Meeting ID
64847033219
Host
Nuria Catalan Lasheras
Alternative host
Marçà Boronat
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Attending: Paz Alonso Arias (PAA), Nuria Catalan Las Heras (NCLH), Mareike Wendelmuth (MW), Matteo Volpi (MV), Igor Syratchev (IS), Anisullah Baig (AB), Ping Wang (PW), Lee Millar (LM), Olivier Brunner (OB)
News from Australia. Restarted the conditioning of windows. Japanese suggested conditioning as function of pulse width. Seeing BD clusters, but at the load, not the windows. PRR=10 Hz. Visual inspection was ok, and vacuum very good too (10e-9). Correlation on vacuum (vacuum spikes between the two windows, but BD on load).
High Gradient Workshop news. To be approved by department. Eleanor will send information after this. CERN is going to cover Frascati prices (120eu/night, tight in Rome). NCLH thinks better to stay in Frascati in terms of logistic. MV booked two apartments, says they can be cheaper (possibility to look into).
CERN Xboxes news. Updates on installation of temperature sensors and flow meters to tune heat losses in structure. PAA will calibrate all lines related to structure B, seeing that the calibration was so old that we were having 10 less power. MW asks how it can be so off, data seemed right when both structures were being conditioned at the same time. MV and IS comment on calibration of directional couplers.
IS says to calibrate lines with 1-0 ratio, make sure of it, then calibrate 50-50. Doubts on what 50-50 was before.
DC down has an offset which we don’t know were it comes from. Systematic offset, MW to just take it off for the moment. Difference between xbox3 and xbox2, probably due to Faraday cups according to NHCL and LM. NHCL is bias was changed by Jan, LM doesn’t remember, source of strange noise never understood. Features in pulse of dark current never done because it was too noisy.
NCLH asks how is MW aligning. MW comments that PSIA and PEIA are easy to align by the rising flag, but PSRA is not. IS says to align by the same amount, because you don’t know where in the structure is the BD occurring. IS says that structure is not fully matched, so we will always have reflected power (30 dB match). So we could align a normal pulse, with no BD. NCLH says doing that would help us with the localization of the BD, and see if we get same result.
MV comments that calibrate reflection channels is tricky, because it bounces a lot. Signal in reflection channels is not very stable, and small. So, use the line of a reflection channel to measure at other point, insertion channel, to calibrate at higher power. PAA not sure about calibrating reflecting channels at higher power (good for BD but not for not BD pulses). If we want to study not BD pulses, and reflected power in this cases, we should calibrate at low power. We have log detectors, which we could use.
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