Author(s): Machado, Ana Amélia Bergamini, 1975- ; Segreto, Ettore, 1973-
Date: 2018
Persistent ID: https://hdl.handle.net/20.500.12733/1664508
Origin: Oasisbr
Subject(s): Difusão; Argônio líquido; Detectores de projeção de tempo (Física nuclear); Diffusion; Liquid argon; Time projection chambers (Nuclear physics); Electron diffusion constant; Artigo original
Agradecimentos: This work was supported by the US NSF (Grants PHY-0919363, PHY-1004072, PHY-1004054, PHY-1242585, PHY-1314483, PHY-1314507 and associated collaborative grants; grants PHY-1211308 and PHY-1455351), the Italian Istituto Nazionale di Fisica Nucleare (INFN), the US DOE (Contract Nos. DE-FG02-91ER40671 and DE-AC02-07CH11359), the Russian RSF (Grant No 16-12-10369), and the Polish NCN (Grant UMO-2014/15/B/ST2/02561). We thank the staff of the Fermilab Particle Physics, Scientific and Core Computing Divisions for their support. We acknowledge the financial support from the UnivEarthS Labex program of Sorbonne Paris Cite (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02), from Sao Paulo Research Foundation (FAPESP) grant (2016/09084-0), and from Foundation for Polish Science (grant No. TEAM/2016-2/17)
Abstract: We report the measurement of the longitudinal diffusion constant in liquid argon with the DarkSide-50 dual-phase time projection chamber. The measurement is performed at drift electric fields of 100 V/cm, 150 V/cm, and 200 V/cm using high statistics Ar-39 decays from atmospheric argon. We derive an expression to describe the pulse shape of the electroluminescence signal (S2) in dual-phase TPCs. The derived S2 pulse shape is fit to events from the uppermost portion of the TPC in order to characterize the radial dependence of the signal. The results are provided as inputs to the measurement of the longitudinal diffusion constant D-L, which we find to be (4.12 +/- 0.09) cm(2)/s for a selection of 140 keV electron recoil events in 200 V/cm drift field and 2.8 kV/cm extraction field. To study the systematics of our measurement we examine data sets of varying event energy, field strength, and detector volume yielding a weighted average value for the diffusion constant of (4.09 +/- 0.12) cm(2)/s. The measured longitudinal diffusion constant is observed to have an energy dependence, and within the studied energy range the result is systematically lower than other results in the literature
FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP
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