TREX-DM: a low background Micromegas-based TPC for low mass WIMP detection

F J Iguaz,F Aznar,D González-Diaz,T Dafni,G Luzón,J F Castel,A Peiró,S Cebrián,A Lagraba,A Rodríguez,H Gómez,I G Irastorza,J A García,J G Garza

doi:10.1088/1742-6596/650/1/012005

Abstract

Dark Matter experiments are recently focusing their detection techniques in low-mass WIMPs, which requires the use of light elements and low energy threshold. In this context, we present the TREX-DM experiment, a low background Micromegas-based TPC for low-mass WIMP detection. Its main goal is the operation of an active detection mass ~0.300 kg, with an energy threshold below 0.4 keVee and fully built with previously selected radiopure materials. This article describes the actual setup, the first results of the comissioning in Ar+2%iC4H10 at 1.2 bar and the future updates for a possible physics run at the Canfranc Underground Laboratory in 2016. A first background model is also presented, based on Geant4 simulations and a muon/electron discrimination method. In a conservative scenario, TREX-DM could be sensitive to DAMA/LIBRA and other hints of positive WIMPs signals, with some space for improvement with a neutron/electron discrimination method or the use of other light gases.

Highlights

The experimental e ort of Dark Matter searches [1] has focused for many years on the search for Weakly Interactive Mass Particles (WIMPs) of relatively large masses
We have considered two light gas mixtures at 10 bar: Ar+2%iC4H10 and Ne+2%iC4H10, which are good candidates to detect low-mass WIMPs and give a total active mass of 0.30 and 0.16 kg respectively
A wide range of materials and components used in TREX-DM detector has been measured in terms of radiopurity: the vessel, the field cage, the shielding, the readout planes and the electronics acquisition system

Summary

Introduction

The experimental e ort of Dark Matter searches [1] has focused for many years on the search for Weakly Interactive Mass Particles (WIMPs) of relatively large masses (of around 50 GeV or larger). Recent advances in radiopure Micromegas readout planes [4], in the selection of radiopure materials for TPCs [5] and in electronics [6, 7, 8] are improving the low-background Prospects and scalability of Micromegas-based TPCs. As part of the T-REX project2, a prototype to assess the feasibility of a low-mass WIMP detector has been developed: TREXDM.

Results

Conclusion