Matthew Moulson for the LAV Working Group NA62 Photon-Veto Working Group Meeting Liverpool, 28 August 2013 LAV construction & installation status

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 A10 at a glance: Where we stand 2 2 layers installed; cabling of layer 2 in progress

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June Considerations for A10 Vessel arrived at Frascati 12 Jul with significant construction delays Layers 3 and 2 installed – currently cabling layer 2 All blocks and bananas ready for installation A10 ready for shipping by beginning of October Signal flange missing! Loaned to CHANTI – currently mounted on vacuum chamber in ECN3 3 signal connectors apparently leak Needs to be fixed and brought back to Frascati ASAP

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June A9 transport Standard packaging procedures: rock wool insulation + thermal blankets Exceptionally good thermal stability Alarm from thermal blanket at 35°C – alarm set point too low ShockLog data recorders work will with 3.6 V LiSOCl 2 batteries Storage in Gran Sasso night before transport Start of transport Mont Blanc tunnel Repeated alarms afternoon of 18/06 Recorders dismounted − vessel − truck

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June A9 transport Acceleration data [g] − transverse − longitudinal − vertical Truck Vessel Loading Storage Transport Offloading No suprises!

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 A12 wrapping: Conclusions from last time 6 Current status: Verified that material can be laser cut Ordered 2m sample cut from roll to develop wrapping technique Next steps: Try to wrap a block with new samples, fewer seams Compare count rates to block with original OPAL wrapping Need to develop test stand for light-tightness tests in production Need to develop block-processing techniques with a mind to minimizing scuffs and tears Will almost certainly need to provide an additional layer of light tightness by closing or draping the A12 volume

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 Trial wrapping for A12 7 Obtained 810 mm × 2 m sample of dyMat T to make trial wrapping with 1-piece template

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 Trial wrapping for A12 8 Critical issue for wrapping: sealing to stainless steel mounting flange Tape and/or wrapping material cannot occupy area on top of flange Surface must be flush with A12 frame for mechanical precision Reinforcement plates create small channels at corners of block where light can enter Attempted solution: 1.Tightly wrap reinforcement plates with black tape to create inner layer 2.Seal wrapping to inner layer of black tape with more black tape Must test to verify light tightness

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 A12 wrapping patterns for laser cutting 9 Single-piece wrapping: 190 covers/100-m roll 2 rolls needed - 40 m left over Two-piece wrapping: 350 covers/100-m roll 1 rolls needed – 15 m left over Plan to make 300 covers dyMat T available in rolls: 810 mm x 100 m = 81 m 2 Cost: €9/m 2 = €729/roll

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 Summary 10 A9 transport successful A10 ready for shipping by beginning of October Urgently need to repair missing A10 signal flange and deliver to Frascati Progress on A12 wrapping, but various aspects still need work: Final details for cut-out pattern (e.g. 1 piece or 2) Assembly tools and procedure Test stand for light leaks and test procedure Local meeting at Frascati next week to discuss A12 wrapping

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 Notes on wrapping for A12 11 A12 wrapping must: Provide light tightness for operation in ambient light Present a (diffusively) reflective surface to interior of glass Separate black and white wrappings can be used if necessary, but a single laminate would be a simpler solution Be resilient against scuffs and tears Be able to be folded around the block Usually means the material has to be thin Be able to be laser cut, ideally Commercial solution: dyMat T (Coveme, Italy) 37.5 μm black PVF + 75 μm PET μm white PVF Not halogen free, requires a safety derogation Good opacity Effectiveness of 37.5 μm black PVF (Tedlar) well established Reasonable price: 810 mm x 100 m roll = 81 m 2 ~ €700 Total thickness ~175 μm: Somewhat difficult to crease, but possible

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 Validation of wrapping material 12 Try to wrap a block using A4-size samples Initial observations: Bad idea to try to tape together A4 sheets to do this Photo tape will never work – need derogation request for PVC tape Try to measure count rates with oven (scaler_main) and oscilloscope, with various lights shining on block About 300 Hz with 6 mV threshold (oven), but not highly reproducible Dark rate in closed oven ~ 1-3 Hz Conclusion: material is probably sufficiently light tight, but need to develop high-quality, reproducible wrapping procedure