CHIPS Event Reconstruction and Design Optimisation

TL;DR

This paper details the simulation, event reconstruction algorithms, and design optimization for the CHIPS water Cherenkov detector, demonstrating effective neutrino interaction identification with low photocathode coverage.

Contribution

It introduces a comprehensive simulation and reconstruction framework for CHIPS, optimizing detector design with 6% coverage using 3-inch PMTs for effective neutrino event analysis.

Findings

Achieved required efficiency and purity for nu_e interactions at 6% coverage.

Successfully reconstructed pi-zero mesons with low photocathode coverage.

Compared performance of 10 inch and 3 inch PMTs in simulations.

Abstract

The CHIPS experiment will comprise a 10 kton water Cherenkov detector in an open mine pit in northern Minnesota, USA. The detector has been simulated using a full GEANT4 simulation and a series of event reconstruction algorithms have been developed to exploit the charge and time information from all of the PMTs. A comparison of simulated CCQE nu_mu and nu_e interactions using 10 inch and 3 inch PMTs is presented, alongside a comparison of 10% and 6% photocathode coverage for 3 inch PMTs. The studies demonstrate that the required selection efficiency and purity of charged-current nu_e interactions can be achieved using a photocathode coverage of 6% with 3 inch PMTs. Finally, a dedicated pi-zero fitter is shown to successfully reconstruct a clean sample of pi-zero mesons despite the low 6% photocathode coverage with 3 inch PMTs.