Experimental observation of an extremely high electron lifetime with the ICARUS-T600 LAr-TPC

TL;DR

This paper reports the successful operation of the ICARUS T600 liquid Argon TPC, achieving an electron lifetime exceeding 15 ms due to advanced purification, demonstrating a significant milestone for large-scale LAr-TPC detectors.

Contribution

It presents the first demonstration of extremely high electron lifetime in a large LAr-TPC, enabling better charge collection and detector performance.

Findings

Electron lifetime exceeded 15 ms

Argon purity reached about 20 ppt of O2 equivalent

Successful operation over 3 years at Gran Sasso

Abstract

The ICARUS T600 detector, the largest liquid Argon Time Projection Chamber (LAr-TPC) realized after many years of RD activities, was installed and successfully operated for 3 years at the INFN Gran Sasso underground Laboratory. One of the most important issues was the need of an extremely low residual electronegative impurity content in the liquid Argon, in order to transport the free electrons created by the ionizing particles with a very small attenuation along the drift path. The solutions adopted for the Argon re-circulation and purification systems have permitted to reach impressive results in terms of Argon purity and a free electron lifetime exceeding 15 ms, corresponding to about 20 parts per trillion of equivalent O2 contamination, a milestone for any future project involving LAr-TPC's and the development of higher detector mass scales.