Operation meeting 07.07.2017 Kevin Fusshoeller, Laura Molina Bueno - PowerPoint PPT Presentation

1 Summary HV Tests Operation meeting 07.07.2017 Kevin Fusshoeller, Laura Molina Bueno

2 Schematics of the detector and HV configuration Anode (nominal voltage: 0V) 2mm 1mm LEM nominal voltage: -1 kV (up) and -4kV (down) Gas Argon 5 mm 5 mm Extraction Grid (nominal voltage: -6.5kV) 20 mm First Field Shaper (FFS) (nominal voltage: -7.5kV) Liquid Argon 1m e - Cathode (nominal voltage: -56kV) PMT‘s

3 Anode (nominal voltage: 0V) CAEN LEM Up (nominal voltage: -1 kV) 0.5 G Ω Max: 8kV, 20 µA 160 M Ω Resolution: 50 pA 150 M Ω LEM Down (nominal voltage: -4 kV) CAEN 130 M Ω 0.5 G Ω 110 M Ω CAEN Extraction Grid (nominal voltage: -6.5kV) 10 G Ω Max: 12kV, 100 µA spare Resolution: First Field Shaper (FFS) 100 M Ω (nominal voltage: -7.5kV) Max: 300 kV, 500 µA Total resistance: 1 G Ω Resolution: 1 kV, 1 µA x 20 -> 2 G Ω x 20 -> 2 G Ω Heinzinger 100 M Ω Cathode (nominal voltage: -56kV)

4 LEM Mapping N S W Comment: The interlock is set, such that as soon as the current on a LEM exceeds 0.2 µA (trip value), the power supply is shut down (trip).

Summary of achieved HV configurations 5 Case 1) Normal operation: Cathode powered with FFS connected, Grid powered, LEM down and up powered Cathode FFS Grid LEM Voltage [kV] Drift Extraction Amplification Induction Comments Voltage Voltage Voltage Field in Liquid [kV/cm] Field Down Up [kV] [kV] [kV] [V/cm] [kV/cm] [kV/cm] 55 2.75 4.5 2.6 0.1 550 1.54 25 0.5 Highest Drift Field achieved. 48 6.5 5.3 1.9 0 480 2.99 19 0 Highest extration while powering all the HV system. 35 4.7 4.1 3.1 0.2 350 1.53 29 1 Highest amplification achieved when powering all the HV system. 37 5 ~4.0 ~3.1 0.2 370 1.08 29 1 For now most stable configuration for data taking. Case 2) Only Cathode and Grid powered. 50 6.75 5.5 0 0 500 4.8 0 0 Highest grid and FFS voltage achieved when powering only grid and cathode. Achieved with 6 mm of liquid above the grid. Case 3) Only Grid and LEM powered. 0 0 4.2 3.3 0.3 0 0.9 30 1.5 Highest amplification. Achieved when the cathode was not powered. Case 4) Only Grid powered. 0 0 4.6 0 0 0 4.5 0 0 /

HV Tests: Lessons learned 6 1. The grid is the most sensible part of the HV system. In all the tests performed, the grid is the first to trip. Extraction grid: Test of 30.06 trips

HV Tests: Lessons learned 7 2. The maximum voltage reachable on the grid depends on the liquid level. (LEMs always grounded) We need to have at least 5 mm of liquid above the grid to reach voltages larger than 4 kV.

HV Tests: Lessons learned 8 3. No obvious correlation between trips and short-time variations of the level, as soon as the grid is immersed. Extraction grid and Level (29.06) Level very stable. LM-CRP8 Grid Voltage

HV Tests: Lessons learned 9 4. When the grid trips, we can also have LEMs tripping. This can happen at the same time or with a delay. All LEMs (top: up LEMs; bottom: down LEMs) 05.07 5 mins later LEM 8, 11 up and down trip, as well Grid trips first LEM 6 up and as LEM 2,4,5, 7 down. down trip at the same time

HV Tests: Lessons learned 5. Depending on which grid connection is used, different LEMs tripped early. LEMs and FFS at ground during this test. Grid connection Inside Grid connection Inside

HV Tests: Lessons learned 11 6. Summary of LEM trips induced after the grid tripped. CRP2 CRP3 LEM Up 0 trips 0 trips 0 trips 1 trip1 0 trips 2 trips LEM Down 4 trips 4 trips 4 trips 5 trips 3 trips 6 trips N S CRP5 CRP1 5 trips 0 trips 1 trip 2 trips 1 trip 0 trips 13 trips 4 trips 5 trips 12 trips 2 trips 2 trips CRP8 CRP7 CRP6 W Plot of the LEM‘s , the liquid level and the number of trips for all tests. The brightest regions are the least immersed and the darkest the most immersed. The least immersed level meter is CRP8, the most one is CRP7.

12 Conclusion and future prospects • The instability of the grid is the biggest challenge so far. We are investigating this issue to understand the source of the problem. • We will take data at different stable high voltage configurations to define the best settings.

13 Backup HV Tests of last week

14 Summary of the tests. Day Level (CRP Liquid above Grid Voltage FFS Voltage Tracks Run Info LEM Voltage [kV] Delta V [kV] 8) [mm] Grid [mm] [kV] [kV] Down Up Grid – LEM - LEM LEM 28.06 16.9 9.4 -4.9 0 0 -5.4 -4.9 0.0 / 10 GOhm resistor connected to grid. The grid and all the LEM down tripped. 28.06 16.9 9.4 -4.9 0 0 -5.4 -4.9 0.0 / Grid disconnected from 10 GOhm resistor. LEM 3 and 8 trip with the grid. 28.06 16.9 9.4 -4.9 0 0 -5.4 -4.9 0.0 / We used the other flange connection to power the grid. The grid tripped and again LEM 3 and 8 trip with the grid. 28.06 16.9 9.4 -1.5 -1.5 0.1 2.7 0 1.4 / Stable configuration for 15h 29.06 16.9 9.4 -3.9 -2.8 -0.2 -4.9 -1.1 -2.6 Yes DAQ turned on during all tests and data constantly taken. LEM down 10 tripped with Grid.

15 Summary of the tests Day Level (CRP 8) Liquid above Grid Voltage LEM Voltage [kV] FFS Delta V [kV] Tracks Run Info [mm] Grid [mm] [kV] Voltage [kV] Down Up Grid – LEM LEM - LEM 29.06 16.9 9.4 -4.5 LEM 1,3,12: - -0.2 -5.5 Max: -1.8 Max: -2.8 Yes DAQ on 2.8 Grid tripped, then LEM 10 LEM 10: -2.7 down, then LEM 5-8 down, All other: -3.0 then LEM 10 up 30.06 16.9 9.4 -4.0 -3.0 -0.4 -4.9 -1.0 -2.6 Yes Positive PMT‘s on. Data taken for a few minutes. Then only the grid tripped. 30.06 16.9 9.4 -3.8 -3.1 -0.4 -4.9 -0.7 -2.7 Yes Data taken for a few minutes. Then the grid and LEM 10 up and down tripped. 30.06 16.9 9.4 -3.8 -3.0 -0.2 -4.0 -0.8 -2.8 / Positive PMT‘s turned off. Grid and LEM down 6 tripped. 30.06 16.9 9.4 1.5 1.5 0.1 -2.7 0 1.4 / HV was left on during the whole night. Electronics were switched on but no data was taken. Everything was stable.

16 Summary of the tests Day Level (CRP 8) Liquid above Grid Voltage FFS Tracks Run Info LEM Voltage [kV] Delta V [kV] [mm] Grid [mm] [kV] Voltage Down Up [kV] Grid – LEM LEM – LEM 01.07 16.9 9.4 -4.1 -3.1 -0.2 -4.7 -1.0 -2.9 / All PMT‘s off. Last configuration stable for 20 mins. The grid and LEM 7 down and up and LEM 4 down tripped, when the electronics were switched on. 04.07 16.9 9.4 -4.6 0 0 0 -4.6 0 / Only the grid was powered during this test and this through the connection in the north slow control flange. It was stable at 4.0 kV for more than 2 hours. It tripped while ramping up to 4.8 kV. LEM 3 and 8 dwon tripped as well. 05.07 16.9 9.4 -4.2 -3.3 -0.3 0 -0.9 -3.0 (Max) / Only the grid and the LEM (LEM 1,3, 10, 12 were powered. When the at -2.9 kV) grid tripped, LEM 6 up and down tripped as well. A few minutes later more LEMs trip: LEM 2, 4,5, 7 down; LEM 8, 11 up and down

29.06.2017 : Overview Grid and Level Run 3 17 LM-CRP8 Grid Voltage Except for a big variation around 15:00, the level is very stable throughout the tests. In the box, we tripped with a delay in certain LEMs. (see next slide)

HV Test 29.06: LEM Downs 18 Original trip Delayed trip

04.07: Run with only the grid powered 19 Manage to reach extraction field of 4.5 kV/cm in the liquid

20 05.07: Only LEMs and Grid powered.

21 05.07: Only LEMs and Grid powered. LEM 6 Grid and LEM 6 up and down trip at the same time

22 05.07: Only LEMs and Grid powered. LEM 8 Delayed trip with response in the grid current. Original trip

23 Reminder from last Operation meeting: Summary of trips on LEM CRP3 CRP2 LEM Up 0 trips 0 trips 0 trips 0 trips 0 trips 0 trips LEM Down 3 trips 2 trips 2 trips 2 trips 2 trips 2 trips N S CRP1 CRP5 5 trips 0 trips 0 trips 1 trip 0 trips 0 trips 9 trips 1 trip 1 trip 6 trips 0 trips 1 trip CRP8 CRP7 CRP6 W Plot of the LEM‘s , the liquid level and the number of trips. The brightest regions are the least immersed and the darkest the most immersed. The least immersed level meter is CRP8, the most one is CRP7.

24 Summary of trips on LEM 28.06 – 05.07 CRP3 CRP2 LEM Up 0 trips 0 trips 0 trips 1 trip 0 trips 2 trips LEM Down 1 trip 2 trips 2 trips 3 trips 1 trip 4 trips N S CRP1 CRP5 0 trips 0 trips 1 trip 1 trip 1 trip 0 trips 4 trips 3 trips 4 trips 6 trips 2 trips 1 trip CRP8 CRP7 CRP6 W Plot of the LEM‘s , the liquid level and the number of trips. The brightest regions are the least immersed and the darkest the most immersed. The least immersed level meter is CRP8, the most one is CRP7.