Measurement of isotopic separation of argon with the prototype of the cryogenic distillation plant Aria for dark matter searches

Abstract

The Aria cryogenic distillation plant, located in Sardinia, Italy, is a key component of the DarkSide-20k experimental program for WIMP dark matter searches at the INFN Laboratori Nazionali del Gran Sasso, Italy. Aria is designed to purify the argon, extracted from underground wells in Colorado, USA, and used as the DarkSide-20k target material, to detector-grade quality.In this paper, we report the first measurement of argon isotopic separation by distillation with the 26 m tall Aria prototype. We discuss the measurement of the operating parameters of the column and the observation of the simultaneous separation of the three stable argon isotopes: 36 Ar, 38 Ar, and 40 Ar. We also provide a detailed comparison of the experimental results with commercial process simulation software.This measurement of isotopic separation of argon is a significant achievement for the project, building on the success of the initial demonstration of isotopic separation of nitrogen using the same equipment in 2019.

The DarkSide-20k underground argon procurement chain

“…In 2021, the second Seruci 0 test was performed with argon; for all the details see ref. [10]. Figure 4 shows the separation factor for 40 Ar-36 Ar (S 36−40 ), it reaches a value of around 1.5.…”

“…It consists of three ARIA column parts: the reboiler, the condenser, and one central module (out of 28), together with all the auxiliary equipment of the final column. Additional details about this column can be found in [10].…”

DarkSide-20k: Next generation Direct Dark Matter searches with liquid Argon

“…The same approach is followed for DarkSide-20k [4], UAr is extracted from an underground CO 2 well (Urania plant, in Cortez, CO, USA) that contains Ar free from the activated 39 Ar. UAr will be further chemically purified to detector-grade Ar in a 350 m cryogenic distillation column (Aria facility, Sardinia, Italy), to remove non-Ar isotopes [5]. An assessment of 39 Ar presence on UAr samples will be performed with the DaRT detector [6] at the Canfranc Underground Laboratory (LSC) in Spain.…”