# A Light Calibration System for the ProtoDUNE-DP Detector

## TL;DR

This paper presents a LED-based fiber calibration system for the ProtoDUNE-DP detector's photon detection system, enabling in-situ PMT calibration and performance monitoring to improve event reconstruction accuracy.

## Contribution

The paper introduces a novel LED-based fiber calibration system specifically designed for the ProtoDUNE-DP detector, serving as a prototype for the DUNE far detector's PDS calibration.

## Key findings

- Successfully validated the calibration system in the ProtoDUNE-DP setup.
- Achieved equalized PMT response for improved trigger threshold consistency.
- Demonstrated in-situ monitoring of PMT performance.

## Abstract

A LED-based fiber calibration system for the ProtoDUNE-Dual Phase (DP) photon detection system (PDS) has been designed and validated. ProtoDUNE-DP is a 6x6x6 m3 liquid argon time-projection-chamber currently being installed at the Neutrino Platform at CERN. The PDS is based on 36 8-inch photomultiplier tubes (PMTs) and will allow triggering on cosmic rays. The system serves as prototype for the PDS of the final DUNE DP far detector in which the PDS also has the function to allow the 3D event reconstruction on non-beam physics. For this purpose an equalized PMT response is desirable to allow using the same threshold definition for all PMT groups, simplifying the determination of the trigger efficiency. The light calibration system described in this paper is developed to provide this and to monitor the PMT performance in-situ.