Microchannel cooling for the LHCb VELO Upgrade I

TL;DR

This paper details the development, production, and performance of silicon microchannel coolers with bi-phase 7b2 for thermal management in the LHCb VELO Upgrade I, marking the largest application of this technology to date.

Contribution

It presents the design, production, and testing of microchannel coolers for the LHCb VELO upgrade, highlighting their performance and suitability for high-energy physics experiments.

Findings

Excellent thermal performance demonstrated

Low and uniform mass of cooling structures

Radiation hardness confirmed

Abstract

The LHCb VELO Upgrade I, currently being installed for the 2022 start of LHC Run 3, uses silicon microchannel coolers with internally circulating bi-phase \cotwo for thermal control of hybrid pixel modules operating in vacuum. This is the largest scale application of this technology to date. Production of the microchannel coolers was completed in July 2019 and the assembly into cooling structures was completed in September 2021. This paper describes the R\&D path supporting the microchannel production and assembly and the motivation for the design choices. The microchannel coolers have excellent thermal peformance, low and uniform mass, no thermal expansion mismatch with the ASICs and are radiation hard. The fluidic and thermal performance is presented.