LAV construction: Status and overview Matthew Moulson (Frascati) for the LAV Working Group NA62 Photon-Veto Working Group Meeting CERN, 25 May 2011 Overall construction status Flanges and cables for A6-A11 Mechanical tests for broken blocks Plans for A3 repair

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 LAV construction status: a snapshot 2 A1 Reconstruction in progress 4 of 5 layers installed A2 22 broken blocks to be replaced Complete reconstruction for recabling planned Shipping to Frascati scheduled tomorrow (26 May) A3 3 blocks to be replaced Complete inspection and test to be performed Work to be scheduled (late June/early July?) A4Ready for installation in ECN3 A5 Shipped from Frascati yesterday (24 May) Will arrive in ECN3 today A6 About 90 blocks of type 13 ready (of 240 total) Banana plates being manufactured at INFN Pisa Vessel under construction at Fantini

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Measurement and survey of A5 3

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 A6 vessel construction 4 Welds completed and tested for flange stacks and manhole Final machining in progress as of 23 May days needed for completion Final vacuum test planned for week of 06 Jun

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Signal/LED flanges for A1-A5 5 LED HV Sig Layer 0 Layer 1 Layer 2 Layer 3 Layer 4 Bans 0-3 Bans layers of 8 bananas = 160 blocks FEE needs 16 ch/connector (4 bananas) Convenient to use 1 flange each, Sig & LED Cable lengths: Sig = 415/515 cm LED = 535 cm LED, Sig

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Proposed signal/LED flanges: A6-A8 6 LED HV Sig 5 layers of 12 bananas = 240 blocks FEE needs 16 ch/connector (4 bananas) Need to use one mixed flange (Sig/LED) Best cable routing has Mix on top Cable lengths: Sig = LED = 650 cm Mix Layer 0 Layer 1 Layer 2 Layer 3 Layer 4 Layer 0 Layer 1 Layer 2 Layer 3 Layer 4 Bans 0-3 Bans 4-7 LED bans 8-11 Sig bans 8-11 LED, Sig Mix

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Proposed signal/LED flanges: A9-A11 7 LED HV Sig 4 layers of 15 bananas = 240 blocks FEE needs 16 ch/connector (4 bananas) Use 4 connectors/layer (= 16 bananas) Last 4 channels on 4 th connector unused Use 2 flanges of 8 connectors for Sig & LED Cable lengths (preliminary): Sig = LED = 740 cm LED Layer 0 Layer 1 Layer 2 Layer 3 Layer 0 Layer 1 Layer 2 Layer 3 Bans 0-3 Bans 4-7 LED, Sig A Sig LED, Sig B Bans 8-11 Bans AB not present 4 ch/con not used

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Broken blocks: an overview 8 Well established that blocks break due to thermal stress A3 transport, A2 storage Various broken blocks in laboratory Blocks are much more susceptible when mounted in bananas Difference of thermal expansion coefficients Mechanical resistance of intact blocks well established by calculations and supported by testing New questions: How are mechanical properties affected if blocks are: Scratched? Know from experience that fractures can start out as scratches Subject to thermal cycles? Already broken? Need to gather statistics

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Testing of scratched blocks 9 Now that we know what to look for, many more scratched blocks found 3 blocks analyzed at Frascati ME3060, ME3141 – type 11 from A3 ME1305 – type 15 from A5 ME1305 Vibration applied with load No crack propagation seen ME3060 Flaw not easily visible at start Becomes visible as load applied No hysteresis Two temperature cycles applied Two-corner break ME3141 Load applied for 10 days Two corner break (maybe temp?) All blocks gradually loaded to 7 bricks (84 kg)

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Load testing 10 Each brick adds a shearing load at the bond equal to that from the lead glass E.g.: 5 bricks = same added stress as 6g acceleration Static loading vs. impulsive loading Static load can test for gradual crack propagation (we wait ~1 hr for failure) Impulsive loads (impact/vibrations) may cause block to be subject to many cycles

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Blocks tested 11 BrokenScratchedThermal cycles 3 corners MD corners ME3141* ME3102 ME2165 ME9735 ME corner ME3060* ME0575 ME2918 ME3623 ME1305 MD ME1881 MD9993 MD7204 * Originally scratched, broken during previous testing + Previously subjected to thermal-cycle testing 10 broken and 5 intact (or scratched) blocks tested to destruction

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Results of load testing >13 0 ME1305 MD5032 ME1881 MD9993 MD ME0575ME2918ME3060ME ME2165ME3141ME3102 ME9735 ME MD9742 Load to failure (lead bricks) Initial damage (broken corners) None of the 5 initially intact blocks failed during these tests (up to 13g) Even heavily damaged blocks can sustain loads of >5g

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Failure modes and role of scratches 13 ME9742: Initial state = 3 corners broken Failure load = 6 bricks ME2165: Initial state = 2 corners broken Failure load = 6 bricks Fracture pefectly matches scoring around base of reinforcement plates

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Broken blocks: Lessons learned 14 Blocks are particularly sensitive to temperature fluctuations Scratches underneath reinforcement plates increase this sensitivity Lesson not fully appreciated until start of A6 construction May have fewer problems with broken blocks in future (A6-A11) Intact blocks have exceptional mechanical resistance Early studies indicated failure loads of 7-10 bricks for unreinforced blocks (see 2008 memo by Cesidio) In our lab, we are not able to safely destroy an intact, reinforced block! Even highly compromised blocks do not fail up to ~5g

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Broken blocks: Implications for A3 15 A3 repair cannot proceed unless we can access to cable tray when layer 4 is up (underneath blocks) Given that damaged blocks can withstand significant static loads: Can we work in area underneath blocks? Can we work freely or do we need to construct special scaffolding? What type of documentation is needed for safety sign-off? A3 repair setup Feb 2011

LAV construction status – M. Moulson (Frascati) – Photon Veto WG – CERN – 25 May 2011 Broken blocks: Implications for future 16 Tests suggest that even damaged blocks may be quite strong Need to refine position on what to do about broken blocks in future? Ideas for discussion: Always repair groups of broken blocks? Always repair blocks with multi-corner fractures? Repair isolated, single corner fractures if easily feasible?