Forum on Tracking Detector Mechanics 2026

Session

Forum Session 4

Jun 3, 2026, 8:25 AM

Maria Luisa (Hotel Hermitage)

Conveners

Forum Session 4: Forum Session 4

• Bart Verlaat (CERN)
• Paolo Petagna (CERN)

44. Commissioning Status and Performance of 2PACL CO₂ Cooling Systems for the ATLAS and CMS Phase-2 Detector Upgrades

Youri Penders

6/3/26, 8:30 AM

For the Phase-2 upgrade of the ATLAS and CMS experiments, new generation 2PACL cooling systems will be installed for the thermal regulation of the inner tracking and timing detectors. A commissioning campaign is currently ongoing to validate operational readiness and characterize system performance.

The ATLAS system has been the focus of initial system verification and final development...

40. Early results from the Surface Storage

Viren Bhanot (CERN)

6/3/26, 8:50 AM

The 'Surface Storage' module is one of the biggest (and most visible) changes to the Two-Phase Accumulator Controlled Loop principle, developed specially to deal with the requirements from CMS and ATLAS for the Hi-Lumi Phase-2 upgrade.

This 12 m3 surface storage vessel will store all the extra CO2 that cannot be stored in the cavern due to space constraints. Flow to/from the underground is...

35. Lessons learned from ATLAS and CMS 2PACL CO2 cooling systems installation for both mechanics and controls.

Jerome Daguin (CERN), Lukasz Zwalinski (CERN)

6/3/26, 9:10 AM

Within the framework of CERN’s High Luminosity LHC program, the ATLAS and CMS experiments are progressing in the installation and hardware commissioning of their environmentally sustainable, low-temperature detector cooling systems. These two-phase accumulator-controlled loop (2PACL) systems are unprecedented in scale and complexity—both mechanically and in terms of control systems—than any...

30. Thermal and Pressure Drop Testing Campaigns of CO₂ Detector Transfer Lines for the CMS experiment

Levent Kilinc (CERN)

6/3/26, 9:40 AM

Detector Transfer Lines (DTLs) are a key element of the CMS Tracker two-phase CO₂ cooling system. They are responsible for distributing liquid CO₂ from the instrumented manifolds at the detector periphery into the detector volume. Their coaxial design (either one or four inner process pipes inside an outer process pipe) allows heat exchange between the liquid supply and the two-phase return,...

48. Experimental testing of a TBPX cooling manifold: validation of the capillary design methodology

Mr Lorenzo Bistoni (Universita e INFN, Perugia (IT)), Pier Filippo Cianchetta (CERN)

6/3/26, 10:35 AM

This study presents experimental tests on a TBPX cooling manifold conducted at CERN.

The objective is to validate the design methodology for all CMS Tracker capillaries, which is based on the modelling and simulation of different cooling loops (grouped by their manifold) using the Multiline tool.

The tested manifold, which groups seven lines, is the most complex and unbalanced one in the...

17. A Predictive Model for Dryout Onset in Milli Scale CO₂ Two Phase Cooling Channels

Dr Joe Dawe (University of Bath (GB))

6/3/26, 11:00 AM

Two phase CO₂ cooling is increasingly adopted in low temperature and high heat flux applications across detector and tracking system infrastructures, where its favourable thermophysical properties offer significant potential for compact, low mass thermal management solutions. However, the onset of dry-out remains a critical design concern: while partial boiling enhances heat transfer,...

46. Experimental investigation of saturation temperature and pipe roughness effects on CO2 microchannel flow boiling for detector cooling

Giacomo Antonini (Università degli Studi di Perugia and CERN), Gian Marco Cioffi (Universita e INFN, Perugia (IT) and CERN)

6/3/26, 11:20 AM

Two-phase evaporative CO$_2$ cooling is a leading solution for the thermal management of silicon detectors, enabling high heat removal with limited material budget and nearly isothermal operation in compact geometries. Nevertheless, reliable prediction of flow boiling heat transfer coefficients (HTCs) and the interpretation of the observed trends remain challenging in micro-scale channels,...