Speaker
Description
The time projection chamber (TPC) requires its working gas to be thermally stabilized within ±0.1 K to preserve a uniform electron drift velocity across the drift volume. This is achieved with a leakless water-circulation system (LCS), where the coolant pressure is kept below ambient so that any breach draws air inside rather than leaking water onto electronics. A key design challenge is the narrow pressure budget between leaks (>1 atm) and cavitation (<0.1 atm), which is further reduced due to viscous friction and hydrostatic pressure due to height of the detector. The LCS was engineered using a fluid network model based on 1D Navier-Stokes equations on the graph edges (pipe segments), with conservation of mass and momentum enforced at the nodes to represent junctions and manifolds.
Laboratory tests demonstrated PID-controlled temperature non-uniformity within ±0.08 K. Precision thermometry is provided by 260 channels, using per-channel correction maps and polynomial sensor calibration to reach ±0.03 K accuracy. For gas-line conditioning, a shell-and-tube heat exchanger reduced the gas-to-water temperature difference by 10-15 times over 20-200 L/min gas flow. The TPC LCS is planned to be commissioned in the first phase of the MPD detector in year 2026.
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