# Precision Luminosity of LHC Proton-Proton Collisions at 13 TeV Using Hit-Counting with TPX Pixel Devices

## TL;DR

This paper demonstrates that a network of Timepix pixel detectors can measure LHC proton-proton collision luminosity at 13 TeV with high precision and stability, using hit-counting techniques during 2015 data-taking.

## Contribution

It introduces a stand-alone TPX pixel detector network for precise luminosity measurement and analyzes its performance during LHC 13 TeV collisions.

## Key findings

- Achieved 0.1% short-term precision in 10 s intervals
- Long-term stability below 0.5% over data-taking period
- Validated the capability to monitor luminosity reduction accurately

## Abstract

A network of Timepix (TPX) devices installed in the ATLAS cavern measures the LHC luminosity as a function of time as a stand-alone system. The data were recorded from 13 TeV proton-proton collisions in 2015. Using two TPX devices, the number of hits created by particles passing the pixel matrices was counted. A van der Meer scan of the LHC beams was analysed using bunch-integrated luminosity averages over the different bunch profiles for an approximate absolute luminosity normalization. It is demonstrated that the TPX network has the capability to measure the reduction of LHC luminosity with precision. Comparative studies were performed among four sensors (two sensors in each TPX device) and the relative short-term precision of the luminosity measurement was determined to be 0.1% for 10 s time intervals. The internal long-term time stability of the measurements was below 0.5% for the data-taking period.