Performance study of a 3×1×1 m³ dual phase liquid Argon Time Projection Chamber exposed to cosmic rays

Abstract

A: We report the results of the analyses of the cosmic ray data collected with a 4 tonne (3×1×1 m 3 ) active mass (volume) Liquid Argon Time-Projection Chamber (TPC) operated in a dual-phase mode. We present a detailed study of the TPC's response, its main detector parameters and performance. The results are important for the understanding and further developments of the dual-phase technology, thanks to the verification of key aspects, such as the extraction of electrons from liquid to gas and their amplification through the entire one square metre readout plain, gain stability, purity and charge sharing between readout views.

Scintillation light detection in the 6-m drift-length ProtoDUNE Dual Phase liquid argon TPC

“…The ionization charge is then extracted, amplified, and detected in gaseous argon above the liquid surface by the charge readout planes (CRPs). The DP technology allows a good signal to noise ratio (> 10 for 6-m drift at 500 V/cm drift field) and a fine spatial resolution ( ) [ 9 ] enabling the construction of large active volumes making efficient use of the LAr volume. The CRP consists of the extraction grid which bounds the active volume, large electron multipliers (LEMs) to produce the charge avalanche, and the anode to collect the electrons.…”

Scintillation light detection in the 6-m drift length ProtoDUNE Dual Phase liquid argon TPC

“…The clear difference between the two different WLS points to a delayed emission time by the WLS material, as proposed in [13,14]. Figure 2 (right) shows a decrease of 𝜏 slow with the ProtoDUNE-DP drift field, as reported in [12]. A model is proposed in [13], taking into account the quenching of the long-lived triplet states through the self-interaction with other triplet states or through the interaction with molecular Ar + 2 ions.…”

“…Waveforms are well described by a sum of three exponential functions convoluted with a Gaussian function to represent the detector response. Although the scintillation time profile should in principle have only two components, from the decay to ground state of singlet (𝜏 fast ) and triplet (𝜏 slow ) argon excimers, an intermediate component (𝜏 int ) is added in order to improve the fit as reported also by other LAr experiments [12]. To get the scintillation decay times from the PMT waveforms, signals from cosmic muons are selected by triggering on a TPB-coated PMT with a minimum amplitude of 25 PEs.…”

Scintillation light detection in the 6-m drift length ProtoDUNE Dual Phase liquid argon TPC

“…The ionization charge is then extracted, amplified, and detected in gaseous argon above the liquid surface by the charge readout planes (CRPs). The DP technology allows a good signal to noise ratio (> 10 for 6m drift at 500 V/cm drift field) and a fine spatial resolu-tion (∼ 3.125 × 3.125 × 0.64 mm 3 ) [9] enabling the construction of large active volumes making efficient use of the LAr volume. The CRP consists of the extraction grid which bounds the active volume, large electron multipliers (LEMs) to produce the charge avalanche, and the anode to collect the electrons.…”