A study of trench-isolated Low Gain Avalanche Detectors (LGADs) examines how the distance between adjacent pixels varies with depth inside the sensor, a parameter that proves critical for detecting radiation that deposits energy near the device surface. The work targets the design of segmented sensors able to pinpoint where ionizing particles strike, a task in which the electrical response depends sensitively on electrode geometry.

LGADs are silicon detectors with a gain layer that multiplies the signal through controlled avalanche, delivering timing resolutions of tens of picoseconds. Segmenting them into pixels adds spatial resolution but introduces the problem of electrical isolation between channels: without proper isolation, induced charge leaks into neighbouring pixels and degrades positional accuracy. Trench isolation is one technique used to confine the charge to a single pixel, and its effectiveness depends on the depth at which the particle deposits its energy.

The study characterises the effective inter-pixel distance as a function of charge deposition depth, showing that it is not constant across the sensor thickness. This depth dependence has direct implications for reconstructing the impact position of particles that lose energy in the detector's surface layers, where positional precision is most sensitive to electrode configuration and local electric fields.

The results are relevant to the design of the next generation of high-granularity, high-timing-resolution silicon detectors planned for high-energy physics experiments as well as for medical imaging and dosimetry applications. Understanding how inter-pixel distance varies with depth allows the trench geometry and reconstruction algorithms to be optimised, improving spatial resolution for shallow radiation detection.