Evaporative CO2 cooling using microchannels etched in silicon for the future LHCb vertex detector

TL;DR

This paper explores the use of microchannel etched silicon for evaporative CO2 cooling to meet the stringent thermal and radiation requirements of the LHCb vertex detector, presenting initial prototypes and design considerations.

Contribution

It introduces the first microchannel prototypes with circulating two-phase CO2 and compares experimental results with simulations, proposing a practical detector design.

Findings

Microchannel prototypes successfully circulated two-phase CO2.

Experimental results align with simulation predictions.

Design considerations for upgraded LHCb VELO detector are discussed.

Abstract

The extreme radiation dose received by vertex detectors at the Large Hadron Collider dictates stringent requirements on their cooling systems. To be robust against radiation damage, sensors should be maintained below -20 degree C and at the same time, the considerable heat load generated in the readout chips and the sensors must be removed. Evaporative CO2 cooling using microchannels etched in a silicon plane in thermal contact with the readout chips is an attractive option. In this paper, we present the first results of microchannel prototypes with circulating, two-phase CO2 and compare them to simulations. We also discuss a practical design of upgraded VELO detector for the LHCb experiment employing this approach.