Dual-Phase status: progress on 3x1x1 prototype L. Molina Bueno on behalf of WA105 collaboration DUNE monthly collaboration meeting, 14th July 2017
The WA105 collaboration demonstrate the capabilities of the dual phase technology at the kton scale 22 institutes 138 physicists, 10 countries 2
Goals of Dual-phase LAr TPC prototype at CERN Demonstrate technical feasibility for O(10kton) detectors • Large surface charge readout in dual-phase scalable to O(10kton) scale detectors • Charge readout with 3mm pitch in two collection views • Long drift distances • High voltage to generate drift field • Production and QA/QC chains for all detector elements • Validation of installation sequence in view of underground detector assembly Conceptual design for DUNE dual-phase 10kton LAr TPC is described in DUNE CDR Vol. 4 arXiv:1601.02984 Operation and measured performance of the prototype at CERN informs DUNE TDR (CD2 review in 2019) 3
Two dual phase liquid argon detectors Same technology → different sizes → different goals in construction Common aspects ✓ LEMs and anode: design, purchase, cleaning and QA ✓ chimneys, FT and slow control sensors ✓ membrane tank technology ✓ Accessible cold front-end electronics and DAQ system ✓ amplification in pure Ar vapour on large areas 11 m in commissioning 5 m 3x1x1 m3 protoDUNE-DP 4
The 3x1x1 m3 Dual phase LAr TPC ✓ First GTT constructed cryostat for LAr ✓ Fully engineered versions of many detector components with pre-production and direct implementation (installation details and ancillary services) ✓ First overview of the complete system integration : set up full chains for Quality Assessment, construction, installation and commissioning ✓ Anticipate legal and practical aspects related to procurement, costs and schedule verification ✓ short term data taking with cosmics 5
The role of CERN: Neutrino Platform 3x1x1-DP large support from CERN Neutrino platform cryogenic installation (piping+ monitoring) cryostat DCS infrastructure (clean room, structures,..) & safety handling, lifting operations,.. 6
The role of CERN in addition to the support from Neutrino Platform, important assistance from many CERN groups and labs PMT coating and anode+LEM: EP-DT-EF photogrammetry + survey EN-ACE-SU polymers: TE-MSC-MDT qualification EP-DT-EF SMD soldering cabling and grounding installation cold bath test, cryolab TE-CRG-CI TE-MPE-EM EP-DT-DI SEM observations: EN-MME-MM drift cage profile bending: EN-MME-FW main workshop cabling manufacturing EN-EA-CT LEM thickness measurements EP-UAT 7
Detector installation- on schedule 8
Detector commissioning and first results 2016 2017 Dec Jan Feb Purge in Beginning closed loop of purge: purging of main pipes Purge in open loop 9
Detector commissioning and first results 2016 2017 Dec Jan Feb RMS pedestal measured at 1.74 ADC PMTs synchronised with Purge in Beginning CRTs trigger. Data in GAr closed loop of purge: was subsequently acquired. purging of main pipes systematic check of noise Purge in All HV connections and open loop sensors tested before cool down pulsing to check detector response Online display to constantly monitor the different sensors. A Slack account for the collaboration was created with different channels to report the daily activities. 10
Light measurements in GAr and trigger 2 Cosmic Ray Tagger pannels with a trigger rate of 0.3 Hz 11
Detector commissioning and first results Mar 1st cool down trial 45 temperature sensors along the insulation space 12
Detector commissioning and first results Mar Apr May I nspections inside to ensure there were no leaks. Filling process: The filling of the detector GTT started inspecting the 3rd cool started progressively and the evolution of cold insulation and drilling holes. down trial regions was monitored in the process. Cryostat works ongoing in the meantime to understand the source of cold spots. Measurement of the gradient of temperature in the gas during cool down 13
Detector commissioning and first results Mar Apr May Jun Jul I nspections inside to ensure there were no leaks. Filling process: The filling of the detector GTT started inspecting the 3rd cool started progressively and the evolution of cold insulation and drilling holes. down trial regions was monitored in the process. Cryostat works ongoing in the meantime to understand the source of cold spots The source of cold spots was identified by CERN and GTT. Due to an anomalous convection produced in gaps between the insulation panels the heat load of the cryostat was 4.5 kW. After injecting a double component foam in several places the heat load was significantly reduced. The injection finished at the beginning of July. Measurement of the gradient of temperature in the gas during cool down 14
Detector commissioning and first results May Mar Very high voltage tests performed in May at different LAr levels. Cathode and field cage powered up to 50 kV in stable conditions. Total resistance of the field cage: 15
Detector commissioning and first results Jun Mar On June 9th CRP position adjusted to its nominal level. On June 12th recirculation started. By June 15th a total of 7 volumes had been recirculated. 16
Evidence for extraction and electroluminescence • Long runs (several 10’s electroluminescence ktriggers per run) - data being PMT raw signal analysed. (“S2") • Example of event acquired with scope: • -1kV on bottom LEM, -3 kV on the grid, -20 kV on preliminary the cathode → drift, extraction, drift in gas, prompt (“S1”) ~500 V/cm EL inside LEM holes ~640us drift • Observe millisecond drift in scope trace → evidence one muon crossing the entire volume at two different drifts for good liquid argon PMT raw signal purity and long drift. electroluminescence (“S2") electroluminescence (“S2") preliminary prompt (“S1”) ~200 V/cm ~1ms drift prompt (“S1”) Time (200µs/div) 17
Light-CRT synchronised events -1kV on bottom LEM, -3.5 kV on the grid, -50 kV on the cathode preliminary 18
Detector commissioning and first results Jun Mar On June 9th CRP position adjusted to its nominal level. On June 12th recirculation started. By June 15th a total of 7 volumes had been recirculated. On June 20th first track One of the very first events with un-optimized field parameters: Drift field 0.32 kV/cm, extraction field 0.6 kV/cm, Raw data- no noise filtering induction field 1 kV/cm. Amplification field in the LEM 29kV/cm (gain ~5). 19
Noise and dead channels in warm and cold ASICs insertion via 2 m blade uTCA crate cold ASICs Pedestal RMS [# e-] 2000 1000 Channel 300 250 accessible cold 200 amplifiers at 150 K. 150 Sealed in chimney separate from main 100 argon volume 50 0 3 2 1 Pedestal RMS [ADC] Pedestal RMS [ADC] 3 Pedestal RMS [# e-] 2000 2 1000 1 650 700 750 800 850 900 950 350 400 450 500 550 600 0 50 100 150 200 250 300 Channel Channel Channel (20adc=3fC) Test pulse at warm and at cold: 17 (1.3%) dead or problematic channels. Low noise condition at cold: 1.66 adc counts (1600 e - ) RMS noise 20
Detector commissioning and first results Jun Jul Mar We identify liquid level variations due to instabilities in the cryogenic system periodic variation Level meter measurement The condenser and phase separator were not well regulated We activate an interlock on the HV system to switch it o ff in case this happens again Time 21
LAr level Camera’s movies provide very useful information! 22
LAr level • The level is adjusted and constantly monitored using 7 capacitive level meters on the CRP , and 5 along the drift cage . Since middle June, this information is also sent to the cryogenic system to constantly regulate the system to keep CRP level meters the level stable . • 4 cryogenic cameras are recording pictures continuously. DC level meters RMS of the fluctuations 0.1 mm 23
Detector commissioning and first results Jun Jul Mar Beginning of HV tests and data taking. Since beginning of this week, we have implemented the possibility of sending a trigger performed by the PMTs to the charge. Trigger rate of 3 Hz Raw data- no noise filtering 24
HV configuration Several HV tests and data taking campaigns performed since beginning of June at different configurations and different LAr levels. During operations we have always stayed below the nominal operating voltages as the extraction grid trips before reaching its nominal value . This limits the extraction efficiency, the induction field and the field across the LEMs. Anode Induction 0 kV Current reached Induction Field 5 kV/cm 1-1.5 kV/cm Field values LEM up -1 kV • LEM field: 29 kV/cm Gain ~6 LEM Field LEM field • Extraction field in 30 kV/cm LEM down -4 kV Extraction liquid: 0.9-1.5 kV 0.4-0.8 efficiency Extraction field in -6.5 kV Extraction grid 2 cm liquid > 2 kV/cm First Field shaper (FFS) -7.5 kV . . Current reached . 1 m values Drift field Cathode 500V/cm Plot from TDR -56 kV PMTs 25
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