Recoil Directionality Studies in Two-Phase Liquid Argon TPC Detectors

¹ Physics Department, Università degli Studi, Cagliari 09042, Italy
² Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, Cagliari 09042, Italy
³ Physics Department, Università degli Studi di Pisa, Pisa 56127, Italy
⁴ Istituto Nazionale Fisica Nucleare, Sezione di Pisa, Pisa 56127, Italy
⁵ Physics Department, Università degli Studi di Genova, Genova 16146, Italy
⁶ Istituto Nazionale di Fisica Nucleare, Sezione di Genova, Genova 16146, Italy
⁷ Physics Department, Università degli Studi Federico II, Napoli 80126, Italy
⁸ Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Napoli 80126, Italy
⁹ Istituto Nazionale di Fisica Nucleare, Sezione di Roma 1, Roma 00185, Italy
¹⁰ Physics Department, Sapienza Università di Roma, Roma 00185, Italy
¹¹ Università di Enna KORE, Enna 94100, Italy
¹² Istituto Nazionale Fisica Nucleare, Laboratori Nazionali del Sud, 95123 Catania, Italy
¹³ Università di Enna KORE, Enna 94100, Italy
¹⁴ Physics Department, Princeton University, Princeton, NJ 08544, USA
¹⁵ Istituto Nazionale Fisica Nucleare, Laboratori Nazionali del Gran Sasso, Assergi (AQ) 67100, Italy

^a e-mail: matteo.cadeddu@ca.infn.it

Published online: 5 December 2017

Abstract

Projects attempting the direct detection of WIMP dark matter share the common problem of eliminating sources of background or using techniques to distinguish background events from true signals. Although experiments such as DarkSide have achieved essentially background free exposures through careful choice of materials and application of efficient veto techniques, there will still be a high burden of proof to convince the greater scientific community when a discovery is claimed. A directional signature in the data would provide extremely strong evidence to distinguish a true WIMP signal from that of an isotropic background. Two-phase argon time projection chambers (TPCs) provide an experimental apparatus which can both be scaled to the ton-scale size required to accommodate the low cross-section expected for WIMP interactions and have an anisotropy that could be exploited to evaluate the polar angles of the resulting nuclear recoils from WIMP collisions with target nuclei. Our studies show that even a modest resolution in the polar angle reconstruction would offer a powerful tool to detect a directional signature. In this contribution, the status of the ReD experiment, which is under construction at Naples University, will be also shown. The aim of the project is to assess and enhance the directionality of two-phase argon TPCs. ReD will use a small TPC exposed to a beam of mono-energetic neutrons to study the so called “columnar recombination” in liquid argon. This development could have high impact on the future experiments in the field, opening up the potential to find conclusive evidence for dark matter or disprove the WIMP hypothesis at and above the mass range explored by planned accelerator experiments.