Advanced mechanical characterisation of two phase CO2 cooling pipe connections for the CMS tracker upgrade at CERN

Project: Research-related funding

Project Details


CERN is the world’s largest high energy particle physics laboratory, which is based in Geneva Switzerland. In order to probe the fundamental behaviour of the universe, CERN’s engineers are required to achieve some of the world most extreme technical requirements and to produce vast accelerator systems such as the Large Hadron Collider (LHC). One of the main experiments within the LHC complex is the Compact Muon Solenoid (CMS) – a 14,000 tonne detector capable of resolving the one billion proton-proton interactions which are produced each second in its core.

The University of Bath and CMS have recently signed an affiliation agreement in order to make use of Bath’s state-of-the-art facilities and internationally renowned research team to tackle some of the extreme technical challenges at CERN. In this regard, Bath is initiating a PhD project focused on the £76 million CMS tracker upgrade, which is due to be installed in 2024. The tracker is the part of the detector closest to the collision, and uses over 6,000 connections per square centimetre to provide 75 million read-out measurements at a resolution of 10 µm.

The proximity of the detector to the collisions means that it receives the highest intensity radiation, and therefore effective cooling is required. Two-phase CO2 cooling will be used in the next generation of the tracker, which will be operated at 163 bar and -35ºC. The cooling channels need to be small (1-2 mm diameter) and lightweight (0.1-0.15 mm wall thickness) to minimise radiation shadowing, as well as highly reliable to allow the system to be operated for long periods without maintenance.

The extreme conditions present within the tracker has meant that custom detachable metallic miniature fittings and permanent soldered/brazed/welded connections are necessary. The successful applicant will be involved in the mechanical characterisation of these joints, in order to quantify performance and reliability, and thereby optimise performance. This will involve a combination of simulation and experimental work to perform strength/creep/pressure testing at low temperatures, as well as metallurgical assessment and corrosion studies.
Short title£65,000 (PhD studentship) + £15,000 equipment fund
Effective start/end date18/03/19 → …