An investigation of alternative configurations of the read controllers of the Fermi LAT tracker

TL;DR

This paper explores alternative configurations of read controllers in the Fermi LAT tracker to improve the readout of large events, addressing limitations in current electronics and their impact on data collection.

Contribution

It introduces new configurations of read controllers for the Fermi LAT tracker and analyzes their potential to enhance event readout capabilities.

Findings

Alternative configurations can increase the number of hits read out per event.

Certain configurations improve the completeness of data collection for large events.

Trade-offs include potential increases in complexity or data handling requirements.

Abstract

The Fermi Large Area Telescope (LAT) consists of 16 towers, each incorporating a tracker made up of a stack of 18 pairs of orthogonal silicon strip detectors (SSDs), interspersed with tungsten converter foils. The strip numbers of the struck strips in each SSD plane are collected by two read controllers (RCs), one at each end, and nine RCs are connected by one of eight cables to a cable controller (CC). The tracker readout electronics limit the number of strips that can be read out. Although each RC can store up to 64 hits, a CC can store maximum of only 128 hits. To insure that the photon shower development and backsplash in the lower layers of the tracker don't compromise the readout of the upper layers, we artificially limit the number of strips read out into each RC to 14, so that no CC can ever can see more than 126 hit strips. In this contribution, we explore other configurations that will allow for a more complete readout of large events, and investigate some of the consequences of using these configurations.