Cooling Analyses of HV-MAPS detector in Compton Polarimeter in Hall A of JLab

The Measurement of a Lepton-Lepton Electroweak Reaction (MOLLER) experiment anticipates new dynamics beyond the Standard Model. The measurements are acquired by the scattering of longitudinally polarized electrons off unpolarized electrons in a liquid hydrogen target using a set of detectors in Hall A at the Thomas Jefferson National Accelerator Facility (JLab) in Newport News, Virginia, USA. MOLLER will use High Voltage-Monolithic Active Pixel Sensors (HV-MAPS) in the Hall A’s Compton polarimeter to monitor the polarization. The detector contains a quad-planar geometry and each plane has three HV-MAPS chips attached. Compton polarimeter requires the HV-MAPS to be placed inside the vacuum to allow for the detection of the scattered electrons. The chips generate heat during operation, and thus require an effective cooling system. The temperature measurement of the HV-MAPS in vacuum is essential to understand the thermal properties of the pixel detector and cooling needs. This project reviews the efforts towards the cooling strategies, structure modification, and thermal simulations to achieve an in-vacuum operation. Further, the prototyping and successful testing of the electron detector’s cooling system (using a test version of HV-MAPS chips with equivalent heat load) in a local lab was performed, and computational fluid dynamics studies are compared with the collected data.