Assessment of backgrounds of the ANAIS experiment for dark matter direct detection

Abstract

A large effort has been carried out to characterize the background of sodium iodide crystals within the ANAIS (Annual modulation with NaI Scintillators) project. In this paper, the background models developed for three 12.5-kg NaI(Tl) scintillators produced by Alpha Spectra Inc. and operated at the Canfranc Underground Laboratory are presented together with an evaluation of the background prospects for the full experiment. Measured spectra from threshold to high energy in different conditions are well described by the models based on quantified activities. At the region of interest, crystal bulk contamination is the dominant background source. Contributions from 210Pb, 40K, 22Na and 3H are the most relevant. Those from 40K and 22Na could be efficiently suppressed thanks to anticoincidence operation in a crystals matrix or inside a Liquid Scintillator Veto (LSV), while that from 210Pb has been reduced by improving crystal production methods and 3H production could be reduced by shielding against cosmic rays during production. Assuming the activities of the last characterized detector, for nine crystals with a total mass of 112.5 kg the expected background rate is 2.5 counts/(keV kg d) in the region from 1 to 4 keV, which could be reduced at 1.4 counts/(keV kg d) by using a LSV.

Version as accepted for publication in Eur. Phys. J. C

References in corpus (7)

• The DAMA/LIBRA apparatus
• Radiogenic and Muon-Induced Backgrounds in the LUX Dark Matter Detector
• Tests on NaI(Tl) crystals for WIMP search at the Yangyang Underground Laboratory
• Cosmogenic radionuclide production in NaI(Tl) crystals
• Search for Low-Mass Dark Matter with CsI(Tl) Crystal Detectors
• Analysis of the 40K contamination in NaI(Tl) crystals from different providers in the frame of the ANAIS project
• Bulk NaI(Tl) scintillation low energy events selection with the ANAIS-0 module

Cited by in corpus (27)

• Initial Performance of the COSINE-100 Experiment
• The SABRE project and the SABRE PoP
• First results on dark matter annual modulation from ANAIS-112 experiment
• Background model for the NaI(Tl) crystals in COSINE-100
• Annual Modulation in Direct Dark Matter Searches
• Analysis of backgrounds for the ANAIS-112 dark matter experiment
• Gaseous and dual-phase time projection chambers for imaging rare processes
• Performance of ANAIS-112 experiment after the first year of data taking
• Understanding NaI(Tl) crystal background for dark matter searches
• Cosmogenic production of tritium in dark matter detectors
• ANAIS-112 sensitivity in the search for dark matter annual modulation
• Monte Carlo simulation of the SABRE PoP background
• Cosmogenic activation of materials
• The COSINE-100 Liquid Scintillator Veto System
• Characterization of SABRE crystal NaI-33 with direct underground counting
• Background assessment for the TREX Dark Matter experiment
• Performance of a prototype active veto system using liquid scintillator for a dark matter search experiment
• Radioactive contamination of scintillators
• Light yield determination in large sodium iodide detectors applied in the search for dark matter
• Cosmogenic activation in double beta decay experiments
• Waveform Simulation for Scintillation Characteristics of NaI(Tl) Crystal
• Alpha backgrounds in NaI(Tl) crystals of COSINE-100
• Measurement of low-energy background events due to ${}^{222}$Rn contamination on the surface of a NaI(Tl) crystal
• Long term measurement of the ${}^{222}$Rn concentration in the Canfranc Underground Laboratory
• The role of small scale experiments in the direct detection of dark matter
• Background modeling for dark matter search with 1.7 years of COSINE-100 data
• Background model of the ANAIS-112 dark matter experiment