IBL cooling thermal chock incident 15 October The IBL cooling team

IBL blow off incident The thermal shock incident during the blow-off test has learnt us several wise lessons. As we designed our system to be thermal shock proof during operation, we have underestimated this behavior at stand-still. –Especially during special events, like emptying and filling. –New vacuum transfer lines have too good insulation and can house liquid for longer time than we were used too. Earlier (small) signs are now understood due to blow off incident. Working on solutions to be safe at standstill or during maintenance procedures. Take lessons into account for future detector cooling systems –Eg. IBL is lowest point, perhaps better would have been that the tubing comes from below or has siphons at in and outlets. –The latter requires more realistic distribution piping mock-ups during development phase. 2

Thermal shock incident and following warm-up 3 Thermal shock incident Drops of liquid was able to enter the detector at some occasions, causing min- shocks Warm-up of detector Saturation temperature rise due pressurization (warming up) Blow-off with liquid from bottle System emptying caused a too large difference between detector temperature and 2- phase temperature. => Better focus on standstill behavior

Similar behavior at a warm- up after stop During warm-up after a stop we have seen similar behavior but due to the small difference between detector temperature and 2-phase temperature, the changes were in the order of degrees. Until the incident we did not fully understand the cause as the manifold is designed to by the highest point such that no liquid can enter by gravity. Blow-off incident learned us that an external push is in the system causing this. –Plant safety by-pass seams responsible for the continuous push 4

Normal situation after a stop: System is emptied due to evaporation by ambient heat 5 Ambient heat Gas to accumulator CO2 stored in accu Plant IBL ManifoldJunction box Ambient heat Gas to system Vacuum insulated transfer line Liquid slug

Current issue in IBL Vacuum insulated lines keep liquid for longer time. Plant over pressure valve pushes liquid sluts towards the detector. Sometimes liquid gets as high as the manifold and is pushed into the detector Gravity brings it down to the detector it self 6 Liquid entering warmer detector Liquid slugs are pushed to detector CO2 stored in accu Plant IBL ManifoldJunction box Ambient heat Vacuum insulated transfer line Liquid slug Plant is pressurized by ambient heat and over pressure escapes through vent valve, causing a push through detector Ambient heat Liquid slugs are pushed to detector

Solution to prevent in the future: Installation of a safety by-pass A safety by-pass will be installed –Normally open (safety position is open) –Closed only when circulation through the system by the pump is achieved 7 Ambient heat Gas to accumulator CO2 stored in accu Plant IBL ManifoldJunction box Ambient heat Gas to system Vacuum insulated transfer line Liquid slug Plant Ambient heat A safety by-pass prevents a pressure build up in the liquid line.

nc PV112 PV312 Safety by-pass 2 Normally closed pneumatic valves will be installed (IBL A and B). Valves will be connector to current blow system connection Installation after the bake-out as safety by-pass is also by passing the blow flow when triggered. By-pass valves are warm and similar type as the service manifold

Safety by-pass stop test Plant B-valves were used to simulate a safety by-pass. No observation of entering liquid after stop By-pass will be installed after bake-out 9 Cooling pipe temperatures Stave 01 temperatures Manifold temperatures This looks like the same effect but is due to condensation inside the IBL staves as they are colder due to pixel cooling

AC042 LP101 vent evacuate 6 8 FT106 ⅜” EH106 TT106 TS106 EH101 / EH102 / EH103 TT101 / TT102 / TT103 TS101 / TS102 / TS103 PT101 / PT102 / PT103 HX150 CO 2 system A 100 labels LT142 LT342 FT306 FL304 ⅜” FL306 VP PV110 PT150/ TT150/ SC150 ¼” BD108 PT108 TT108 CO 2 from experiment CO 2 to experiment 42 PT142 PV108 PV144 HX148 TT148 BD148 SV042 SV043 MV042 FL144 MV041 TT146 AV108 Freon chiller A 200 CO 2 system B 300 labels 10 LP101 EH301 / EH302 / EH303 TT301 / TT302 / TT303 TS301 / TS302 / TS303 PT301 / PT302 / PT303 4 FL344 PT304 TT304 MV EH306 TT306 TS306 BD308 PT308 TT308 AV308 PV308 PV310 PV TT346 HX350 HX348 LP301 Fill port nc no nc no nc MV050 MV054 MV052 MV056 BD054 PT054 EV148 EV348 nc 50 PT350/ TT350/ SC350 SV040 MV040 SV041 BD MV058 NV110 MV110 MV310 nc CV142 nc CV342 nc Cold CO2 line Cold R404a line Warm service line (Cold lines require 32mm insulation) no NV310 no ¼” ½” 48 TT348 BD348 Freon chiller B 400 MV043 PT342 BV, PT040 PT042 PT056 PRC142 controlling CV142, EH142/143 (PT142 & SC150) PRC342 controlling CV342, EH342/143 (PT342 & SC350) PT050 PT058 no FL104 4 PT104 TT104 nc FL106 Fill port MV106 EH142/143 TT142/143 TS142/143 FL042 EH342/343 TT342/343 TS342/343 MV012 MV039 AV012