Using machine learning to improve neutron identification in water Cherenkov detectors

Water Cherenkov detectors like Super-Kamiokande, and the next generation Hyper-Kamiokande are adding gadolinium to their water to improve the detection of neutrons. By detecting neutrons in addition to the leptons in neutrino interactions, an improved separation between neutrino and anti-neutrinos,...

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Main Authors: Blair Jamieson, Matt Stubbs, Sheela Ramanna, John Walker, Nick Prouse, Ryosuke Akutsu, Patrick de Perio, Wojciech Fedorko
Format: Article
Language:English
Published: Frontiers Media S.A. 2022-09-01
Series:Frontiers in Big Data
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fdata.2022.978857/full
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author Blair Jamieson
Matt Stubbs
Sheela Ramanna
John Walker
John Walker
Nick Prouse
Ryosuke Akutsu
Patrick de Perio
Patrick de Perio
Wojciech Fedorko
author_facet Blair Jamieson
Matt Stubbs
Sheela Ramanna
John Walker
John Walker
Nick Prouse
Ryosuke Akutsu
Patrick de Perio
Patrick de Perio
Wojciech Fedorko
author_sort Blair Jamieson
collection DOAJ
description Water Cherenkov detectors like Super-Kamiokande, and the next generation Hyper-Kamiokande are adding gadolinium to their water to improve the detection of neutrons. By detecting neutrons in addition to the leptons in neutrino interactions, an improved separation between neutrino and anti-neutrinos, and reduced backgrounds for proton decay searches can be expected. The neutron signal itself is still small and can be confused with muon spallation and other background sources. In this paper, machine learning techniques are employed to optimize the neutron capture detection capability in the new intermediate water Cherenkov detector (IWCD) for Hyper-K. In particular, boosted decision tree (XGBoost), graph convolutional network (GCN), and dynamic graph convolutional neural network (DGCNN) models are developed and benchmarked against a statistical likelihood-based approach, achieving up to a 10% increase in classification accuracy. Characteristic features are also engineered from the datasets and analyzed using SHAP (SHapley Additive exPlanations) to provide insight into the pivotal factors influencing event type outcomes. The dataset used in this research consisted of roughly 1.6 million simulated particle gun events, divided nearly evenly between neutron capture and a background electron source. The current samples used for training are representative only, and more realistic samples will need to be made for the analyses of real data. The current class split is 50/50, but there is expected to be a difference between the classes in the real experiment, and one might consider using resampling techniques to address the issue of serious imbalances in the class distribution in real data if necessary.
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spelling doaj.art-eb9e502a042f4ce884be8b8560353d962022-12-22T04:29:16ZengFrontiers Media S.A.Frontiers in Big Data2624-909X2022-09-01510.3389/fdata.2022.978857978857Using machine learning to improve neutron identification in water Cherenkov detectorsBlair Jamieson0Matt Stubbs1Sheela Ramanna2John Walker3John Walker4Nick Prouse5Ryosuke Akutsu6Patrick de Perio7Patrick de Perio8Wojciech Fedorko9Physics Department, University of Winnipeg, Winnipeg, MB, CanadaApplied Computer Science Department, University of Winnipeg, Winnipeg, MB, CanadaApplied Computer Science Department, University of Winnipeg, Winnipeg, MB, CanadaPhysics Department, University of Winnipeg, Winnipeg, MB, CanadaScience Division, TRIUMF, Vancouver, BC, CanadaScience Division, TRIUMF, Vancouver, BC, CanadaScience Division, TRIUMF, Vancouver, BC, CanadaScience Division, TRIUMF, Vancouver, BC, CanadaKavli IPMU (WPI), UTIAS, The University of Tokyo, Tokyo, JapanScience Division, TRIUMF, Vancouver, BC, CanadaWater Cherenkov detectors like Super-Kamiokande, and the next generation Hyper-Kamiokande are adding gadolinium to their water to improve the detection of neutrons. By detecting neutrons in addition to the leptons in neutrino interactions, an improved separation between neutrino and anti-neutrinos, and reduced backgrounds for proton decay searches can be expected. The neutron signal itself is still small and can be confused with muon spallation and other background sources. In this paper, machine learning techniques are employed to optimize the neutron capture detection capability in the new intermediate water Cherenkov detector (IWCD) for Hyper-K. In particular, boosted decision tree (XGBoost), graph convolutional network (GCN), and dynamic graph convolutional neural network (DGCNN) models are developed and benchmarked against a statistical likelihood-based approach, achieving up to a 10% increase in classification accuracy. Characteristic features are also engineered from the datasets and analyzed using SHAP (SHapley Additive exPlanations) to provide insight into the pivotal factors influencing event type outcomes. The dataset used in this research consisted of roughly 1.6 million simulated particle gun events, divided nearly evenly between neutron capture and a background electron source. The current samples used for training are representative only, and more realistic samples will need to be made for the analyses of real data. The current class split is 50/50, but there is expected to be a difference between the classes in the real experiment, and one might consider using resampling techniques to address the issue of serious imbalances in the class distribution in real data if necessary.https://www.frontiersin.org/articles/10.3389/fdata.2022.978857/fullmachine learninggraph neural networkswater Cherenkov detectorparticle physicsneutrino physics
spellingShingle Blair Jamieson
Matt Stubbs
Sheela Ramanna
John Walker
John Walker
Nick Prouse
Ryosuke Akutsu
Patrick de Perio
Patrick de Perio
Wojciech Fedorko
Using machine learning to improve neutron identification in water Cherenkov detectors
Frontiers in Big Data
machine learning
graph neural networks
water Cherenkov detector
particle physics
neutrino physics
title Using machine learning to improve neutron identification in water Cherenkov detectors
title_full Using machine learning to improve neutron identification in water Cherenkov detectors
title_fullStr Using machine learning to improve neutron identification in water Cherenkov detectors
title_full_unstemmed Using machine learning to improve neutron identification in water Cherenkov detectors
title_short Using machine learning to improve neutron identification in water Cherenkov detectors
title_sort using machine learning to improve neutron identification in water cherenkov detectors
topic machine learning
graph neural networks
water Cherenkov detector
particle physics
neutrino physics
url https://www.frontiersin.org/articles/10.3389/fdata.2022.978857/full
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