2. Cryogenic Systems Juan Casas (TE-CRG-CI) In behalf of the CRG team R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15

3. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: outline of the talk Availability Relocation of commercial equipment: status and plans Cryo-tunnel sensors & actuators: qualification campaign & remaining issues Radiation tolerant custom electronics: expected radiation performance & long-term issues NOT IN THIS TALK: Refrigeration Units, Interconnection boxes & controls: well established maintenance procedures Materials ageing for gaskets, diaphragms, cable insulation, etc.

4. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: Availability Availability of Cryogenic Cooling operation is/WAS impaired by: 26.9 %: Utilities (Electrical supply, water cooling, networks, etc) 14.0 %: Radiation effects 54.1 %: Cryogenic equipment failures 5.0 %: Users Overall availability is better than 91.9 %; it is already an excellent performance. Cryogenics team is continuously looking for optimizing operation, SEU shall disappear However next runs may result in new challenges Availability [%] 2010 Nice learning curve! mostly Cryo issues treated “on the fly” 2011 Good start before beam induced issues (energetic neutrons), 1st corrections 2012 Effective treatment of beam induced issues, A global success ! 2013 830 cumulated days with an average availability of 91.9%

5. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: Availability & LHC Radiation Events Single Events is the only type of observed perturbation induced by the LHC radiation All the affected components were supposed to be located in radiation free areas “Radtol” refers to the custom electronics measuring the leads temperature Sensitive digital-insulator consolidated by end to 2011 => No events in 2012 Availability increases with experience and by applying corrective actions (hardware, software or relocation) During 2012 most of the SEE/SEU were transparent to the LHC availability Commercial equipment was relocated => SEU on commercial equipment not expected for next runs

6. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: Instrumentation & Controls Industrial electronics shall always be located in protected areas Exception: split valve-actuator designed for CERN and qualified in TCC2 Sensors & actuators: qualified during LHC design phase Cryo Rad-Tol electronics: designed for Arc & DSS

7. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: Industrial equipment Industrial/commercial equipment is not qualified for radiation and shall be removed from exposed areas. => relocation campaigns of the most sensible equipment like: Remote IO (Siemens ET200), profibus DP/PA couplers, 24 Vdc power supplies, Sipart valve actuator in UJ14, UJ16, UJ56, UJ67, P4 & P8 Power electronics for the cold-compressor magnetic bearings controller and variable frequency drives in P4 & P8. Note that potentially sensitive equipment like intelligent signal conditioners still remain in P4 & P8 Detailed list to be prepared and commented Commercial electronics shall be relocated along with the rest of the equipment Nothing is planned yet for P2 and P6. Radiation field calculations shall indicate whether yes or no, a relocation is required. Similar equipment also exist in the underground areas of P18, but in a location that is deemed to be free of radiation.

8. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: sensors/actuators Non exchangeable: thermometers and electrical heaters. => Duplication exist for some critical thermometers => No duplication for beam-screen heaters => 100% availability unlikely for about 300 channels! Exchangeable: pressure sensors, liquid helium level gauges, valves motors, etc Qualified for radiation: Split valve positioner piezoresistive valve and feedback potentiometer installed in radiation area Intelligent part integrated profibus interface and controlller installed in protected area Pressure sensor Temperature sensor: next slide May still fail as any industrial device! Assumed to be rad-hard or adequate procedure for maintenance: Superconducting level gauge: identical technology as for magnets Pressure sensors with metallic membranes (new 50 mbar devices) Similar devices used in other radiation areas Qualification too complicated & not worth Cold-mass thermometer on magnetic yoke Replacing a liquid He superconducting Level gauge

9. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: Temperature sensors Most of the sensors were qualified for radiation in nominal operational conditions: Arc: 10 year dose 1.5 10 13 n/cm2, 300 Gy => OK for HL-LHC apart of IT Inner-Triplet: neutron dose will it exceed the qualification dose? Probably yes Saturation of drift: probably true above 10 15 n/cm 2, it is an amorphous structure, however…. Radiation qualification above 10 14 n/cm 2 : too complicated, it has to be done @ 1.8 K INVESTIGATE ALTERNATIVE SOLUTIONS: Exchangeability: insertion capillaries but superfluid helium complicates the design Foresee additional thermometer supports in the vacuum envelope Drawback: IT need to be opened Combine several type of sensors Thermometer @ end-plate of IT

10. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: Tunnel Electronics Design target 1 kGy on single components, compatible with HL-LHC dose estimation Component selection and tests started by 1998. Most sensitive components during “short” IC qualification campaigns: Micro-FIP CC131 & ADC failed by respectively 800 Gy and 500 Gy Annealing repaired the faults => LHC total withstand radiation is certainly higher Some not “properly” qualified dc/dc converter in use for several type of cards NOTE that no problems up to 500 Gy in CNGS tests Thermal design has margin for additional dissipation due to radiation. Crates: Under Dipole:

11. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: New Tunnel Electronics New electrical power supply: Designed to satisfy baking requirements for the LHC beam-screen Good opportunity to consolidate all 500 W heaters relied in a SEE sensitive signal conditioner used for the heater element protection thermometer New components were qualified in CNGS and PSI MOSFET ac switch (FCA36N60NF) Analog multiplexer (SW06GSZ Quad SPST JFET Analog Switch, Analog Devices) Overall radiation performance should be improved with respect to previous design: No DC-DC converter or any other “complicated” IC New insulated temperature card for the current leads Designed to withstand the 1.2 kV test voltage applied during ELQA Adapted for use in the tunnel in order to read temperature sensors with a short-circuit to ground Digital-insulator SEU sensitivity consolidated by implementing a periodical reset NEXT: Final check for new electronic cards in CHARM Tests planned from November 2014 Analog multiplexer: radiation test

12. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: Tunnel Electronics & Availability The LHC readouts and actuators are not only affected by radiation but also by: Ambient temperature and humidity Electromagnetic interference Ageing Mechanical issues due to corrosion, reliability of contacts, … ………………….. Losses of “cryo-maintain” are caused not only by SEU but also by intermittent losses of electrical continuity when it affects a critical channel Furthermore there are thousands of channels with several electrical interfaces each. About 3 such events are observed each year of operation

13. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Cryogenic Systems: Tunnel electronics spare parts & issues The LHC cryo radtol electronics are based on a library components qualified before 2005. For new designs radiation tests are performed if the part is not in our stock of components Some of the components have become obsolete or replaced by new parts, in most cases (but not always) the replacement parts can be expected to have similar radiation performance. Cross-checked by radiation test. New commercial COTS may become available with promising characteristics for radiation: Example is the analog multiplexer selected for new cards. This part simplified significantly the design of the new power supply for the beam screen. LHC spare cards: typically at least 15% of installed base Replacement cards can be produced within 6 month  compatible if end-of-life warning RAD-HARD ASIC: more than 12 k pieces in stock => sufficient for future needs Exception: micro-FIP CC-131 communication card that is not any more available  Spare cards and spare CC-131 modules should permit to cope with MTBF issues  Foresee for 2020 development of new communication interface compatible with the existing crates and cards nanoFIP but a development is required for the handling of the backpanel signals.

14. R2E and Availability Workshop - Cryogenic Systems - JCC 2014.10.15 Conclusions Availability of LHC cryogenics is a complex issue, it is certainly affected not only by the radiation effects on the tunnel electronics, but also by common issues that do exist in any industrial complex (fuses, open electrical connections, interference, etc.). Long term issues of concern: Obsolescence of microFIP CC-131 imposes the development of a new interface to be ready when MTBF issues become a problematic issue Maintenance of reception automated test-benches for new cards manufacturing Existing production test bench is based in LabView and any modification require updating the OS and/or LabView version => lots of effort Last development used the PVSS/CIET environment for automating the test Based on a platform maintained by CERN as it is based in the CERN SCADAs Radiation doses expected in the inner triplets => foresee insertion thermometers Probably not required, but dose exceed qualification parameters Electromagnetic noise: Noise appear when grounding locally some leads What happen when the power converters will not be alongside the lead temperature cards? Until now there is no evidence of increased rate of failures Without personnel in the tunnel failure rate is close to nil