Modeling Light Signals Using Data from the First Pulsed Neutron Source Program at the DUNE Vertical Drift ColdBox Test Facility at CERN Neutrino Platform

TL;DR

This study quantitatively compares detected light signals from a pulsed neutron source in a small LArTPC at CERN with simulations, finding good agreement and providing insights for future larger detectors.

Contribution

First quantitative test of light signals in a pulsed neutron run in a small LArTPC at CERN, validated with detailed simulations and systematic analysis.

Findings

Detected photoelectrons below 650 in both data and simulation

Fitted time constant consistent between data and MC

Systematic effects identified for future larger detectors

Abstract

In this paper, we present a first quantitative test of detected light signals produced in a pulsed neutron source run in a small vertical drift LArTPC at the CERN neutrino platform ColdBox test facility. The ColdBox cryostat, detectors, neutron sources, and particle interactions are modeled and simulated using Fluka. A good agreement is found in the detected number of photoelectrons, with values below 650 photoelectrons in both data and simulation, for all four X-ARAPUCA photodetectors on the cathode in the LArTPC. A time constant is also fitted from the neutron-beam-off light signal spectrum and found consistent between data and MC. Several important systematic effects are discussed and serve as guides for future runs at larger LArTPCs.