Speaker
Description
Resolving the microscopic charge distribution of ionization tracks in liquid noble gases can reveal local energy deposition and interaction topology beyond a measurement of total energy. This information offers opportunities for improved reconstruction of X-ray and gamma-ray interactions, particle identification, and background rejection in rare-event searches. Sensitivity to small charge deposits can further reveal faint track segments and secondary interactions that would otherwise remain unresolved. Achieving these capabilities requires fine pixel pitch and low-noise direct charge sensing without relying on avalanche multiplication. Low power dissipation is also essential to limit local heating and avoid bubble formation during operation in the liquid.
We present a cryogenic charge imager designed for continuous operation. The first prototype comprises an 80-by-80-pixel array with a 50-micrometer pitch. With the pixel front ends continuously powered, the imager achieves an input-referred noise of <30 electrons at cryogenic temperatures using pixel-parallel correlated double sampling, while dissipating less than 1 microwatt per pixel. We will discuss the sensor and readout architecture, measurements of the first prototype, and the prospects for combining fine-scale track imaging with sensitivity to low-energy charge deposits in liquid noble gases.