A model independent parametrization of the optical properties of the refrozen IceCube drill holes

TL;DR

This paper introduces a model-independent method using principal component analysis to interpolate and unify various measurements of the optical properties of refrozen IceCube drill holes, reducing systematic uncertainties in neutrino detection.

Contribution

It presents a novel PCA-based framework to systematically interpolate between different optical property models of drill holes in IceCube, improving analysis consistency.

Findings

Unified systematic variation framework established

Interpolation between multiple optical property models achieved

Reduces uncertainties in neutrino oscillation and cascade reconstructions

Abstract

The IceCube Neutrino Observatory deployed 5160 digital optical modules (DOMs) in a cubic kilometer of deep, glacial ice below the geographic South Pole, recording the Cherenkov light of passing charged particles. While the optical properties of the undisturbed ice are nowadays well understood, the properties of the refrozen drill holes still pose a challenge. From camera observations, we expect a central, strongly scattering column shadowing a part of the DOMs' sensitive area. In MC simulation, this effect is commonly modeled as a modification to the DOMs' angular acceptance curve, reducing the forward sensitivity of the DOMs. The associated uncertainty is a dominant detector systematic for neutrino oscillation studies as well as high-energy cascade reconstructions. Over the years, several measurements and fits of the drill holes' optical properties and of the angular acceptance curve have been proposed, some of which are in tension. Here, we present a principle component analysis, which allows us to interpolate between all suggested scenarios, and thus provide a complete systematic variation within a unified framework at analysis level.