High Voltage Monolithic Active Pixel Sensors for the MOLLER Experiment

The MOLLER experiment aims to measure the parity-violating asymmetry (APV) in electron-electron scattering

at 11 GeV, and thus determine the weak charge of the electron to a high precision (2.4%). Two of the

key sub-systems in the experimental apparatus are the main detector array, consisting of 224 fused silica detector

modules and electron beam Compton polarimeter. The main detector array can be operated in either

pulse mode for particle tracking, or integration mode for high rate detection. A sub-section of these detector

modules will be equipped with an array of High Voltage Monolithic Active Pixel Sensors (HVMAPS), to be

used in particle tracking and allowing for real-time monitoring of the event profile in the main Moller region.

HVMAPS chips are also used for the Compton polarimeter, consisting of multiple planes of HVMAPS chips,

housed in a vacuum chamber upstream of the interaction point. I will provide an overview of the main detector

and Compton polarimeter HVMAPS pixel sensor implementation as well as aspects of the chip design, the module

cooling design, and the development and construction status.