Instrumentation Used in LAPD and 35T Runs (Dune DocDB 1759) Alan Hahn DUNE Cryo Meeting 9/21/16

“Cryo” Instrumentation Purity Monitors Gas Analyzers Temperature (“Precision”) Movable (vertical) and Fixed Video Cameras General Cryo probes DUNE Cryo Meeting 9/21/16

Purity Monitors LAPD & 35 Ton had 5 PrMs Patterned after the ICARUS PrM 2 short (17cm) and 2 long (47 cm) in Cryostat In LAPD and 35T Phase 1 mounted on 2 strings In 35T Phase 2 mounted on single string of 4 In 35T we were limited by the number of available ports In Phase 2, one port became unavailable due to close proximity to HV Feedthru. 1 long PrM positioned just after LAr Filtration Modules DUNE Cryo Meeting 9/21/16

35 Ton PrM String (@PAB) Top Short PrM (#4) Long PrM3 DUNE Cryo Meeting 9/21/16

Gas Analyzers O2, N2, H2O gas analyzers Various sensitivities-see table below Extensively used during Ar Gas Purge and recirculation period to monitor progress Sample either liquid or gas depending on location of pickoff tubing in cryostat. During LAr Phase of running, can be useful to look at outgassing/contamination Highest sensitivity O2 analyzer (< 1ppb) is useful for e- lifetimes < 2 ms From T. Tope DUNE Cryo Meeting 9/21/16

DUNE Cryo Meeting 9/21/16

Precision Temperature Measurements Translating RTD (aka RTD Spooler) 3 RTDs mounted on pcb hanging on chain that can be lowered and raised in both the liquid and gas regions of the cryostat Used in LAPD and 35 Ton Phase 1 run The RTD offsets were adjusted (by eye) to minimize temperature spread while in the liquid (see plot) One issue is that the LAr Bulk liquid temperature depends on Barometric pressure, so runs (could be as long as 24 hrs) were sensitive to this. Plots shown here (~12 hr run for both down and up) were taken from a period where the barometric pressure was reasonably stable Fixed RTDs In 35T Phase 2, there was no location for the RTD Spooler, so instead mounted a RTD on top of each PrM to measure the time dependence of the vertical temperature profile “Precision” was due to averaging in the Lakeshore 218 Temperature Monitor Used 4-wire measurement technique The RTDs were not absolutely calibrated, but instead were used to measure relative changes in temperature. We found that the simple unplugging of the RTD readout cable from the flange (during TPC noise searching) could cause offsets in the RTDs in the order of ~10 mK. Following slides are show the devices and some examples of the measurements we made DUNE Cryo Meeting 9/21/16

RTD Spooler and Fixed RTDs Lakeshore 218 Pump RTD Spooler in 35 Ton Cryostat Pump Intake RTD Mounted on PrM2 DUNE Cryo Meeting 9/21/16

Ullage Temperatures from RTD Spooler Measurements (35T Phase 1 Run) Roughly under lowest Rad Shield DUNE Cryo Meeting 9/21/16

RTD Spooler Measurements Phase 1 (Expanded scale) 50 mK DUNE Cryo Meeting 9/21/16

Power Outage (and pump off) provides another opportunity to verify the stratification. PrM1&4 with 3 Precision RTDs (also at different heights in Cryostat) Pump is off Pump is on 20 mK 3 RTD offsets adjusted to match during this period Barometric Pressure Uppermost RTD 12 hrs after Outage PrM 1&4 show same lifetime PrM 1&4 lifetimes diverge Lowest RTD DUNE Cryo Meeting 9/21/16

Video Cameras Primary Use is to see location of HV breakdowns Secondary uses are to see what is going on during various phases of the cryostat operation. LAPD modified one of the RTD spooler mechanisms to mount a camera. Spooler mechanism allows vertical height changes in order to search for the location of its HV breakdown. However we were wrong on the transverse location and had to rotate its mounting flange to point to the field cage—instead of the HV feed-thru 35 Ton Phase 2 implemented 8 fixed cameras looking at the “likely” suspects where we thought a breakdown might occur. These never saw any light from the various HV breakdowns (~6) we had in the 35 Ton. Various quality of image when we used internal red-led lighting to illuminate the cryostat. See http://dbweb5.fnal.gov:8080/ECL/lbne_35t/E/show?e=5967 All these used inexpensive cameras mounted in a SS housing with a sealed window and positioned in the cryostat. Also included an internal heater which is was necessary to insure that we could cycle power and have the camera still function DUNE Cryo Meeting 9/21/16

Camera Example Link to LAPD elog http://dbweb5.fnal.gov:8080/ECL/lartpc/E/show?e=4321 At bottom of link are links to 3 short movies showing how camera behaved during HV breakdown. Photo at right from Long Bo TPC field cage (in LAPD) http://dbweb5.fnal.gov:8080/ECL/lartpc/E/show?e=4319 Nice Movie of 35T Phase 2 Filling LAr surface moves past a camera http://dbweb5.fnal.gov:8080/ECL/lbne_35t/E/show?e=4499 Click on link—it will animate in a separate window DUNE Cryo Meeting 9/21/16

General Cryo Probes used by Cryo Control System Various RTDs (for temperature) mounted around inside cryostat (usually on membrane surfaces) Pressure probes both relative and absolute. Correlates to LAr temperatures and can effect mixing in the liquid and ullage areas. LAr Level Probes Important for HV LAr Pump parameters All this info has been used to make correlations between cause and effects seen in the cryostats I assume this data is reasonably accessible by users! I argue that system we have at FNAL stretches the word “reasonably” tho’ DUNE Cryo Meeting 9/21/16

Response to Loss of N2 Cooling (Valve failure) DF-560 O2 Analyzer RTD Temp. Probes Cryostat Internal Gauge Pressure Condenser LN2 Level Cryostat LAr Level LN2 runs dry, lose control of internal pressure. Vents at 1.5 psi, LAr Level begins to drop DUNE Cryo Meeting 9/21/16

PrM Response to loss of LN2 (from previous slide) Pressure spikes and drops mix LAr vertically e- Lifetime Bottom PrM (#1) 4.0 ms 3.5 ms Drift-time (~480 us) 3.0 ms 2.5 ms Top PrM (#4) 2.0 ms 1.5 ms Drift time changes (due to higher LAr temp Ullage also seems to be mixed into LAr 1.0 ms 0.5 ms 0.0 ms DUNE Cryo Meeting 9/21/16