Matthew Moulson for the LAV Working Group NA62 Photon-Veto Working Group Meeting CERN, 4 June 2013 LAV construction & installation status

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 At a glance: Where we stand 2

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June A10 construction delays Last meeting: Delivery of A10 vessel delayed to 20 June 2 months delay due to welding tests for A9 More difficult to lathe stainless steel than originally foreseen Delay to 20 June → unlikely to finish before August shutdown A9 transport scheduled for week of 10 June Meeting at Fantini 15 May: Delivery further delayed to 12 July Bottleneck from backup of work for Zayer (large CNC milling machine) Work on A10 suspended from 31 May to 10 June before cutting manhole & nozzles We can afford to be generous goal of finishing before August won’t be met in any case Relax A9 transport schedule to week of 18 June Vacuum test week of 3 June Survey week of 10 June

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June A10 delivery status Suspension of work on A10 31 May – 10 June

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 A12 construction techniques 5 Experimenting with techniques and tools for A12 construction Very likely that blocks will be installed directly into rings No pre-assembled bananas as for A1-11 Experimentation with sling + overhead crane for block manipulation Use this technique instead of lift table? Possible to install last block in ring with this technique?

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 A12 construction techniques 6 With care, sling can be used to install last block in plane into hole with blocks on both sides.

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 A12 construction techniques 7 Important considerations: Cabling scheme – necessary to specify final cable length Wrapping material and technique Completed A12 prototype in laboratory

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 Notes on wrapping for A12 8 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 9 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

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 4 June 2013 Wrapping material: Other considerations 10 Current status: Verified that material can be laser cut Some heat-introduced distortion at edges for small (slow) cuts, but material does not burn or delaminate 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 Can probably adapt oven for this purpose Need a standard source of illumination 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