Mechanical design of the optical modules intended for IceCube-Gen2

TL;DR

This paper details the mechanical design and testing of innovative optical modules for IceCube-Gen2, enhancing neutrino detection sensitivity through advanced PMT integration and pressure vessel design.

Contribution

It introduces two new optical module designs with integrated multi-PMTs and silicone gel coupling, optimized for high-pressure, low-temperature Antarctic conditions.

Findings

Modules operate reliably at 70 MPa pressure

Optical coupling improves photon collection efficiency

Prototypes perform well in simulated environment

Abstract

IceCube-Gen2 is an expansion of the IceCube neutrino observatory at the South Pole that aims to increase the sensitivity to high-energy neutrinos by an order of magnitude. To this end, about 10,000 new optical modules will be installed, instrumenting a fiducial volume of about 8 km^3. Two newly developed optical module types increase current sensitivity per module by a factor of three by integrating 16 and 18 newly developed four-inch PMTs in specially designed 12.5-inch diameter pressure vessels. Both designs use conical silicone gel pads to optically couple the PMTs to the pressure vessel to increase photon collection efficiency. The outside portion of gel pads are pre-cast onto each PMT prior to integration, while the interiors are filled and cast after the PMT assemblies are installed in the pressure vessel via a pushing mechanism. This paper presents both the mechanical design, as well as the performance of prototype modules at high pressure (70 MPa) and low temperature (-40 degree Celsius), characteristic of the environment inside the South Pole ice.