Contacts around LHCb Velo RF box Benoit Salvant
Contacts around LHCb Velo RF box Benoit Salvant, Branko Popovic, Christine Vollinger Thanks to colleagues from IWG, LHCb, SMOG 2 and NIKHEF impedance meeting 04/10/2019
Context • Major upgrade of LHCb detector: new VELO • Discussed with impedance team/IWG since years • Focus since 2017 on the addition of the SMOG 2 cell on one side of the VELO
Complete VELO model with SMOG 2 (Open Position) Closed Open SMOG 2 Model Branko Popovic
Context • Major upgrade of LHCb detector: new VELO • Discussed with impedance team/IWG since years • Focus since 2017 on the addition of the SMOG 2 cell on one side of the VELO • Ad-hoc meeting organised yesterday with SMOG 2 and VELO colleagues to discuss contact issues on the VELO/SMOG 2 side
situation on the SMOG 2 side Observation by SMOG 2 colleagues of RF contact foil deformation (sept 17 th) Request for IWG recommendation
situation on the SMOG 2 side RF box RF foil SMOG 2 Worrying deformation. No point of fixation on RF box side Not clear that contacts are well defined
situation on the SMOG 2 side RF box RF foil SMOG 2 Worrying deformation. No point of fixation on RF box side Not clear that contacts are well defined
situation on the SMOG 2 side SMOG 2 RF foil RF box Worrying deformation. No point of fixation on RF box side Not clear that contacts are well defined
Additional files presented yesterday Worrying deformation. No point of fixation on RF box side Not clear that contacts are well defined
Additional files presented yesterday RF box mockup RF foil SMOG 2 Worrying deformation. No point of fixation on RF box side Not clear that contacts are well defined
Changes to SMOG side WFS Mounting LHC-UNPOL-TARGET_ASB-V 5. stp LHC-UNPOL-TARGET_ASB-V 7. stp Branko Popovic, files from Vittore Carassiti
Picture of the mock-up (Branko Popovic)
Ideas? Make sure that contacts are well defined Ensure that the foil will not fall off on the RF box side (true for the free SMOG 2 arm, the other one has a star and is fixed) To be discussed at IWG
situation on the detector side We have assumed perfect contact so far between the wakefield suppressor and the RF box
situation on the detector side Vittore said that the situation with SMOG 2 was better than the configuration without SMOG 2
situation on the detector side And could even have degraded to this if the foil slides on the mushroom pins Mushroom pins
situation on the detector side And could even have degraded to this if the foil slides on the mushroom pins Worrying situation for the other side of the VELO, if really the situation: - Impedance will increase due to this 2 mm hole, that would be 3. 5 mm from the beam when closed - The contact could be very poor : only the thickness of the foil contacts with the small pin. Could lead to local heat and damage after several cycles.
Where are we? • We warned the LHCb colleagues • We are assessing the exact geometries with them and NIKHEF. • We are looking for solutions to ensure contact, in case it is needed. • RF measurements on a mock-up were done, and the foil was contacting well then, but no cycling was performed to avoid stressing the wakefield suppressor.
- Slides: 18