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Gas systems weekly project meeting
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32/1-A24 (CERN)
gas systems project meeting
Gas systems
Gas systems 2026-09-03
Key Outcomes
The meeting covered team introductions from new technical students, followed by an extensive operational review of gas systems across multiple detectors (RPC, TPC, TOF, TGC, GEM). Key issues include an ongoing pressure increase in Rack 70 requiring root-cause analysis before intervention, a failed power supply on TPC now running on backup, and unresolved circulation pump problems. Several action items were assigned across team members.
New Team Members Introduced
- Michael (Germany): Mechanical engineering student, 6-month technical placement; will work on EAM integration of electronic components with Thomas and Davide, focusing on ATLAS detector upgrades and reverse engineering of TGC systems.
- Henrietta (Hungary): Physics master's student; prior experience with multiwire proportional chambers and RPC performance studies; will continue work on alternative gas mixtures for RPCs.
System Issues & Status
- TPC Power Supply: One power supply confirmed blank/failed; system currently running on the secondary power supply; replacement needed.
- Alarms at 5:30: Both TPC and TOF alarms received simultaneously; a second TPC alarm followed shortly after.
- ATLAS RPC Purifier Pump: Pump restored after maintenance; input valve was the root cause of vacuum failure (gas leaking through input bar). Column A is stable; Column B still has minor leakage and requires monitoring.
- RPC Circulation Pump 2: High inter-membrane pressure detected; operations switched to Pump 3. Pressure rebuilding slowly; CO₂ gas mixture suspected but not confirmed as cause.
- CMS RPC Rack 70 (PC) Pressure Increase: Econex throttled to 30%; pressure slope increasing since early July, coinciding with purifier stoppage. Root cause unclear — possible needle valve deposit or manifold contamination.
- LHCb-UT Pressure Regulator: Handle found to be loose/moving; needs inspection to confirm correct logic.
Decisions Made
- CMS RPC Rack 70 intervention: Do not clean the manifold yet; first replace the needle valve and inspect for deposits before deciding on full manifold dismount.
- Stopping the full rack (3–4 days) is required for complete manifold cleaning; team must assess urgency vs. operational impact before proceeding.
- Further trend analysis needed from January onward to determine if pressure slope change is linked to purifier stoppage.
- Econex replacement on Rack 70 scheduled for September 14.
- All activities — including minor interventions at GIF and non-LHC sites — must be logged in elog and Jira to quantify team workload.
Open Questions & Risks
- Whether Rack 70 pressure increase is caused by manifold deposits, needle valve blockage, or chamber reconnection procedure — trend analysis from January required before intervention.
- Risk of particle contamination in detector pipes if manifold is cleaned without full dismount; particles freed during cleaning could enter small detector input pipes.
- LHCb-UT: Need to verify whether gas flow stopping during system shutdown is the intended behaviour (to be checked with LHCb).
- Space planning: Absorber rack and Compression rack placement under discussion; compressor location not yet confirmed.
Action Items
- Maria Cristina: Generate pressure trend plots for Rack 70 from January (or earlier) to present; organize dedicated discussion before any manifold intervention.
- Patrick: Investigate LHCb-UT pressure regulator — confirm correct logic and pipe condition.
- Andrea : Complete panel for CSC 904; finalize TID and send link.
- Team: verify analysis chains (active/useful status).
- GIF: Monday Sept 7 — assist at GIF to remove an eco-RPC chamber (~2 hours).
- Florian's mixer: Order required materials — planned for next week – who is ordering?
- Mass Flow Controller: Confirm ticket exists in Jira confirming unit was sent.
- Rack storage: Create a kiosk storage area for the tent to list materials we have there -> Miguel.
piquet:
LHCb pump filters to be changed or something (for LS3)-> TICKET
O2+H2O analyser to be checked -> TICKET
ATLAS-RPC rack 66 and 69 pressure alarm during purif 2 change over -> TICKET
NA62
glitch of CEDAR 6105, is it the keller? -> TICKET to check
ATLAS-TGC putifier Col B leak. loosing 1 bar in 1 day -> TICKET Davide check with Argon or CO2
CMS-DT pressure sensor PT1303 went to 0 for 20 minutes -> TICKET to follow Andrea
ATLAS-RPC purif -> affecting chamber pressure -> R66 check
12/2 ATL-RPC purif 1 some software issue and sms not indicating the right reason for the alarm -> TICKET
IR status, spares, .... --> TICKET
test binary gas analyser... -> TICKET
outcome of binary gas analyser test --> TICKET & buy a 2nd one --> Maria Cristina
DP pressure for pump filter in ALICE and LHCb -> TICKET -> @LPh + @Patrick [GASSYSTEMS-903] DP pressure for pump filter increasing - CERN Central Jira -> Stefania
chiller fluids to uniform between CMS, LHCb and ATLAS -> TICKET Maria Cristina
check if NV in purif is really useful --> TICKET
Calibration bottles O2-H2O status
ALICE
70 report from Anité [GASSYSTEMS-70] TPC gas quality - filters to Benoit - CERN Central Jira (I don't see the report, can you please add it?)
several alarms blocked: [GASSYSTEMS-628] ALICE alarms blocked - CERN Central Jira
TOF gas mixture analysis -> [GASSYSTEMS-639] TOF gas mixture analysis - CERN Central Jira & ELOG
TRD membrane is connected ? -> [GASSYSTEMS-717] TRD membrane status - CERN Central Jira
P&ID drawing check who is doing -> [GASSYSTEMS-736] ALICE P&ID drawing check - CERN Central Jira
MID swap of pumps during MD because sometime the system stop -> TICKET
ATLAS
MDT frequency converter (need to be replaced TICKET) ELOG - ATLAS MDT Test convertisseur 4101 avec la pompe 4201
RPC distribution rack regulation valve (TICKET)
RPC secondary mixer (TICKET), info to be given to ATLAS
RPC purif 3 circuit breakers & meeting -> [GASSYSTEMS-718] RPC purif 3 electrical issue - CERN Central Jira --> meeting when?
ATLAS-TGC flow difference --> [GASSYSTEMS-612] ATLAS-TGC flow difference - CERN Central Jira
CMS
RPC purif test at workshop, PLC needed -> TICKET
R134a insulation - isol'tut to check and see what to do -> ticket IO [GASSYSTEMS-578] R134a insulation - isol'tut to check and see what to do - CERN Central Jira
How much gas flow we need for the RPC purifier? --> [GASSYSTEMS-579] CMS-RPC How much gas flow we need for the RPC purifiers? - CERN Central Jira @MariaCristina notes to be added
RPC bypass pump too much closed --> [GASSYSTEMS-604] RPC bypass pump too much closed - CERN Central Jira
RPC with CO2 like ATLAS and effect on R134a recuperation -> [GASSYSTEMS-606] RPC with CO2 like ATLAS and effect on R134a recuperation - CERN Central Jira
R134a Upgrade (hardware and software) to be tested -> [GASSYSTEMS-594] R134a Upgrade (hardware and software) to be tested - CERN Central Jira
DT vaisala reading difference between SG and US -> [GASSYSTEMS-677] CMS DT vaisala reading difference between SG and US - CERN Central Jira
CMS-FGR -> TICKET should we add a module. Do we need to buy something? follow-up
CMS-FGR -> TICKET Maria Cristina già fatto per bypass
CMS-FGR -> TICKET flowmeter for Huber
CMS-RPC IR not stable -> elog Maria Cristina -> TICKET
CMS-ID flushing. refurbishing of old racks material and manpower need to be estimated -> TICKET @Gianluca ticket number for project
R134a huber temperature can be controlled by PLC -> TICKET
LHCb
TS1-> RICH1 leak search (postponed), SciFi some work from others expected
RICH1 what we learn from 1st fill -> [GASSYSTEMS-608] RICH1 what we learn from 1st fill - CERN Central Jira
summary of the C4F10 bottles --> TICKET or ELOG -> [GASSYSTEMS-660] summary of the C4F10 bottles - CERN Central Jira
alarms blocked: [GASSYSTEMS-631] LHCb alarms blocked - CERN Central Jira
RICH2 filter blocking -> [GASSYSTEMS-731] RICH2 pump filter differential pressure sensor not working - CERN Central Jira
P&ID drawing check who is doing -> [GASSYSTEMS-739] LHCb P&ID drawing check - CERN Central Jira
RICH1 cleaning , when? not before mid-september? -> TICKET
RICH1 remove membrane rack before end of HL-LHC operation and/or change piping-> TICKET
RICH2 injection through recuperated CF4 -> TICKET
fire detection alarms reported by Pieter, more info? but not on us. Cleaning of SG room -> TICKET
CODEX-b interlock for flammable gas detection -> Patrick
RICH1 leak repair -> December 9th tbc -> TICKET
NA62
CEDAR maintenance needed -> [GASSYSTEMS-609] CEDAR maintenance needed - CERN Central Jira
change of pressure sensor used for leak warning? -> [GASSYSTEMS-741] NA62-CEDAR move to keller pressure sensor? - CERN Central Jira
GIF++ TGC gas system and return flow: [GASSYSTEMS-624] GIF++ TGC gas system return flow - CERN Central Jira
[GASSYSTEMS-674] MFCs to be checked - CERN Central Jira :
- Fondoscala del MFC di R134A e sensore umidità del gas RPC [GASSYSTEMS-645] Fondoscala del MFC di R134A e sensore umidità del gas RPC - CERN Central Jira
- Neutrino platform gas analysis: [GASSYSTEMS-622] RE: Analisi di outgassing di diversi materiali - CERN Central Jira
- ALICE T10 MFCs: [GASSYSTEMS-669] ALICE T10 TR: calibration MFC pour C4F10 - CERN Central Jira
- ND280 MFCs to check [GASSYSTEMS-679] ND280 MFCs to check - CERN Central Jira
non-LHC safety valve --> check lista di Fabio
[GASSYSTEMS-172] non-LHC safety valves to be verified - CERN Central Jira
ELOG - safety valves to be verified for non-LHC systems
Additional requests/projects/discussions
887 CEDAR new "mixers" --> [GASSYSTEMS-509] CEDAR for beam lines - CERN Central Jira
AMBER
EDMS leak test?
test certificate x-ray?
ATEX certificate?
who is technical coordinator
resource manager Oleg D?
no money? should we stop? and resume in 2026?
Commissioning when? -> TICKET
when they would like to start? Moritz? -> ask
LEAK DETECTORS LIST -> TICKET
MAINTENANCE INTERVENTIONS WORK ORDER FOR STATISTICS -> TICKET
PROJECT 2025
summary TICKET
examples of topics for the common discussions:
-cms id flushing -> Andrea
-cms r134a operation and spare -> Andrea
-cms cf4 operation and spare -> Andrea
-atl tgc nc5h12 -> Kacper
-Analysis boxes -> LPh
-C4F10 new recuperation installation -> Patrick
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