A measurement of the material in the ATLAS inner detector using secondary hadronic interactions

TL;DR

This paper measures the material distribution in the ATLAS inner detector by analyzing secondary hadronic interactions, validating simulation models, and improving the understanding of particle reconstruction.

Contribution

It introduces a method to quantify the detector material using secondary vertices from hadronic interactions in LHC data, with validation against simulations.

Findings

Material description validated within 7% uncertainty

Spatial resolution of secondary vertices ~200 microns to 1 mm

Improved understanding of object reconstruction in ATLAS

Abstract

The ATLAS inner detector is used to reconstruct secondary vertices due to hadronic interactions of primary collision products, so probing the location and amount of material in the inner region of ATLAS. Data collected in 7 TeV pp collisions at the LHC, with a minimum bias trigger, are used for comparisons with simulated events. The reconstructed secondary vertices have spatial resolutions ranging from ~200 microns to 1 mm. The overall material description in the simulation is validated to within an experimental uncertainty of about 7%. This will lead to a better understanding of the reconstruction of various objects such as tracks, leptons, jets, and missing transverse momentum.