A method for precise charge reconstruction with pixel detectors using binary hit information

TL;DR

This paper introduces a threshold-stepping method to accurately reconstruct charge spectra in pixel detectors using only binary hit data, achieving resolutions near the electronic noise limit.

Contribution

It presents a novel threshold adjustment technique that enables precise charge reconstruction independent of the detector's charge readout circuitry.

Findings

Achieved charge resolution below 200 electrons.

Demonstrated method effectiveness with radioactive sources and electron beams.

Performance close to the electronic noise limit of the detector.

Abstract

A method is presented to precisely reconstruct charge spectra with pixel detectors using binary hit information of individual pixels. The method is independent of the charge information provided by the readout circuitry and has a resolution mainly limited by the electronic noise. It relies on the ability to change the detection threshold in small steps while counting hits from a particle source. The errors are addressed and the performance of the method is shown based on measurements with the ATLAS pixel chip FE-I4 bump bonded to a 230 {\mu}m 3D-silicon sensor. Charge spectra from radioactive sources and from electron beams are presented serving as examples. It is demonstrated that a charge resolution ({\sigma}<200 e) close to the electronic noise of the ATLAS FE-I4 pixel chip can be achieved.