On the role of radiative losses in energy scale of large liquid scintillator and water Cerenkov detectors

TL;DR

This paper investigates how radiative losses cause non-linearities in the energy response of large liquid scintillator and water Cherenkov detectors at energies of 5-100 MeV, with implications for neutrino measurements.

Contribution

The study models and simulates the non-linear effects of radiative losses on detector energy scale, highlighting their energy dependence and potential impact on neutrino spectrum analysis.

Findings

Non-linearity grows with Cherenkov light fraction, maxing in pure water detectors.

Effect is sub-percent at 5-10 MeV for all detectors.

Can reach about 5% at 50-100 MeV in water Cherenkov detectors.

Abstract

The scope of this article is to understand the role of radiative losses in detector energy scale at energies of 5-100 MeV and to estimate the non-linear effect they produce in large liquid scintillator and Cherenkov detectors. For this purpose the generalized energy scale detector model was constructed and the detector response was simulated by means of toy Monte Carlo simulations. It was found that the non-linearity grows proportionally to a relative fraction of the Cherenkov light into the total light yield achieving the maximum for pure water Cherenkov detectors. The effect generally increases with energy and then saturates at higher energies. In the energy region 5-10 MeV for all types of detectors and for energies 5-100 MeV in scintillation detectors with low fractions of Cherenkov light ( < 10 % ) the non-linearity is estimated to be a sub- percent effect. Meanwhile it could reach the order of 5% for 50 - 100 MeV electrons in pure water Cherenkov detectors. It was hypothesised that this effect can contribute to the difference in observed reactor neutrino spectra. The present analysis showed that the effect was quite small to generate significant differences in observed reactor neutrino spectra. Though it still may be relevant for precision measurements and phenomenological analysis in aforementioned energy ranges.