Status and performance of mass-produced IceCube Upgrade mDOMs

TL;DR

This paper reports on the production, testing, and deployment status of multi-PMT Digital Optical Modules (mDOMs) for the IceCube Upgrade, which aims to enhance neutrino detection in Antarctica starting in 2025/2026.

Contribution

It presents the first comprehensive status update on mass-produced mDOMs, including automated testing procedures and successful deployment of initial modules.

Findings

Majority of mDOMs produced and tested successfully

All modules on first two strings shipped to the South Pole

Automated testing reduces time and improves quality control

Abstract

IceCube Upgrade, starting in the Antarctic summer season 2025/2026, will enhance the sensitivity of the current IceCube in the GeV range and improve understanding of the ice properties. Around 700 new modules will be deployed deep in the ice along seven strings, spaced $3\,\mathrm{m}$ vertically within a horizontal region of $100\,\mathrm{m}$. IceCube Upgrade mainly consists of two types of Cherenkov photon detectors, $\sim280$ Dual optical sensors in an Ellipsoid Glass for Gen2 (D-Eggs) and $\sim400$ multi-PMT Digital Optical Modules (mDOMs). Here, we present the status of mDOM production and acceptance testing for mass-produced mDOMs. The majority of the modules have already been produced, and all 128 modules on the first 2 strings have been successfully shipped to the South Pole after multiple steps of testing. Each mDOM contains 24 photomultipliers nearly isotropically distributed on the surface to achieve uniform photon sensitivity, making the integration and testing complicated. To reduce the amount of testing time, we have developed parallelized and automated software.