On the limited amplitude resolution of multipixel Geiger-mode APDs

TL;DR

This paper analyzes how the finite number of pixels in Geiger-mode APDs causes non-linearity and fluctuations, ultimately limiting the amplitude and energy resolution of detectors using these devices.

Contribution

It provides a theoretical calculation of the amplitude resolution of ideal G-APDs considering pixel limitations and their impact on detector energy resolution.

Findings

Amplitude resolution is finite due to pixel limitations.

Energy resolution of G-APD-based scintillation detectors is fundamentally limited.

Non-linearity and fluctuations are key factors affecting G-APD performance.

Abstract

The limited number of active pixels in a Geiger-mode Avalanche Photodiode (G-APD) results not only in a non-linearity but also in an additional fluctuation of its response. Both these effects are taken into account to calculate the amplitude resolution of an ideal G-APD, which is shown to be finite. As one of the consequences, the energy resolution of a scintillation detector based on a G-APD is shown to be limited to some minimum value defined by the number of pixels in the G-APD.