Performance studies of a pixel tracker in the Silicon Detector (SiD) concept for a future linear collider

TL;DR

This study evaluates the impact of various pixel tracker configurations in the SiD detector for a future linear collider, revealing that increased granularity improves certain resolutions but offers limited overall benefits.

Contribution

It provides a detailed analysis of how different pixel sizes and geometries affect tracker performance and physics measurements in the SiD detector.

Findings

Replacing silicon strips with pixels greatly improves secondary vertex resolution.

Increasing pixel density enhances momentum resolution for collimated jets.

Granularity upgrades yield limited overall improvements in collider physics performance.

Abstract

Using the simulation framework of the SiD detector to study the Higgs -> mumu decay channel showed a considerable gain in signal significance could be achieved through an increase in charged particle momentum resolution. However more detailed simulations of theZ -> mumu decay channel demonstrated that significant improvement in the resolution could not be achieved through an increase in tracker granularity. Conversely detector stability studies into missing/dead vertex layers using longer lived particles displayed an increase in track resolution. The existing 9.15 cm x 25 {\mu}m silicon strip geometry was replaced with 100 x 100 micrometers silicon pixels improving secondary vertex resolution by a factor of 100. Study into highly collimated events through the use of dense jets showed that momentum resolution can be increased by a factor of 2, greatly improving signal significance but requiring a reduction in pixel size to 25 micrometers. An upgrade of the tracker granularity from the 9.15 cm strips to micrometer sized pixels requires an increase in number and complexity of sensor channels yet provides only a small improvement in the majority of linear collider physics.