Calibration strategy of the PROSPECT-II detector with external and intrinsic sources

TL;DR

This paper develops and evaluates an external calibration strategy for the PROSPECT-II neutrino detector, ensuring precise energy calibration and long-term stability for advanced neutrino physics research.

Contribution

It introduces a new external calibration scheme for PROSPECT-II, replacing internal sources, and demonstrates its effectiveness through simulation and data analysis.

Findings

External calibration achieves comparable performance to internal sources.

Calibration uncertainty meets the experiment's precision requirements.

Simulation confirms robustness across detector configurations.

Abstract

This paper presents an energy calibration scheme for an upgraded reactor antineutrino detector for the Precision Reactor Oscillation and Spectrum Experiment (PROSPECT). The PROSPECT collaboration is preparing an upgraded detector, PROSPECT-II (P-II), to advance capabilities for the investigation of fundamental neutrino physics, fission processes and associated reactor neutrino flux, and nuclear security applications. P-II will expand the statistical power of the original PROSPECT (P-I) dataset by at least an order of magnitude. The new design builds upon previous P-I design and focuses on improving the detector robustness and long-term stability to enable multi-year operation at one or more sites. The new design optimizes the fiducial volume by elimination of dead space previously occupied by internal calibration channels, which in turn necessitates the external deployment. In this paper, we describe a calibration strategy for P-II. The expected performance of externally deployed calibration sources is evaluated using P-I data and a well-benchmarked simulation package by varying detector segmentation configurations in the analysis. The proposed external calibration scheme delivers a compatible energy scale model and achieves comparable performance with the inclusion of an additional AmBe neutron source, in comparison to the previous internal arrangement. Most importantly, the estimated uncertainty contribution from the external energy scale calibration model meets the precision requirements of the P-II experiment.