Speaker
Description
The next generation of high-energy physics experiments demand thermal management solutions to balance power densities with ultra-low material budgets. Within the DRD8 (Mechanics) framework, research is focused on advancing silicon- and ceramic-based microchannel cooling. By placing the coolant in direct proximity to the heat source, these technologies achieve highly efficient heat removal. Current developments emphasize CMOS-compatible fabrication, active interposers for electrical integration, and low-cost silicon processes using hyperbaric bonding, all while aiming for a material budget as low as $0.2\% X_0$.
One of the primary drivers for these innovations is the LHCb VELO Upgrade 2, which serves as a benchmark for high-power scenarios. This detector requires stable operation in a vacuum while sustaining power dissipations of approximately $2\text{ W/cm}^2$ and resisting radiation doses up to $10^{17} \text{ MeV n}_{eq}/\text{cm}^2$. To meet these needs, current designs utilize evaporative $\text{CO}_2$ cooling which requires validation to high pressure (186 bar).
Building on the success of the large-scale $\text{CO}_2$ systems currently being commissioned for ATLAS and CMS, new research is exploring supercritical $\text{CO}_2$ (sCO$_2$) for electronics operating between $+35^\circ\text{C}$ and $+40^\circ\text{C}$. As an electrically non-conductive fluid with low viscosity and high heat transfer coefficients, sCO$_2$ allows for smaller, lighter piping and microchannel integration. This is particularly advantageous for detector regions with confined spaces.
For future detectors requiring Ultra-Low-Temperature (ULT) operation potentially down to $-140^\circ\text{C}$ (in a 2 stage approach), research has shifted toward Krypton (R784). Since $\text{CO}_2$ freezes at $-56.6^\circ\text{C}$, Krypton offers a promising evaporative candidate for the colder environments. Unlike $\text{CO}_2$, Krypton requires a specialized transcritical cooldown cycle to prevent thermal shock during liquefaction. This talk will review the principles of these sustainable cooling architectures and present the latest experimental results designed for future collider applications.