EFFICIENCY AND SENSITIVITY FOR THE HALO

DETECTORCara Esposito

Saint Joseph’s UniversityDr. Kate Scholberg

Duke University

Outline

Brief background on neutrinos, supernovae, and the HALO detector

Efficiency and the important information gained from examining the efficiency

Sensitivity for HALO Summary

Background

•The Equation above is for the probability of detecting flavor g at L for a two flavor case.•Although there are three flavors, the Δm2 remains•Normal Mass Hierarchy (NMH) has one heavy and two light mass states, while IMH has two heavy and one light mass state

Background

Supernovae happen when a massive star can no longer sustain itself and it explodes

99% of the energy of core collapse supernovae is neutrinos

Before After

Background

SNOLab in Canada 79 tons of lead 128 helium

detectors 2 km underground HALO 2 is currently

in the developing phase and will most likely use 1 kiloton of lead

Helium Detectors

Lead

Background

Visualization of the simulation using Geant4

How HALO Works

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How HALO Works

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How HALO Works

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How HALO Works

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How HALO Works

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How HALO Works

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How HALO Works

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Flux

The left panel is for inverted mass hierarchy

The right panel is for normal mass hierarchy

Energy Spectrum

From the energy deposited in the detector we can determine whether it’s a 1N or a 2N event.

Energy Spectrum

From the energy deposited in the detector we can determine whether it’s a 1N or a 2N event.

1N 2n

Efficiency

•Tells us how well the detector works

Sensitivity

HALO 1’s sensitivity for 5kpc supernovae

Contours in which ninety percent of the number of one-neutron and two-neutron events fall

The different colored curves correspond to different spectral parameters

Sensitivity

For 10 kpc supernovae HALO 1 can only constrain extreme models

Sensitivity

HALO 2 ‘s discriminatory power will increase with a greater number of counts for 10 kpc supernovae.

Summary

Simulated neutron events in the HALO Geant4 simulator

Efficiency for 1N events is approximately 36%

Efficiency for 2N events is approximately 56%

HALO 1 has good sensitivity for 5 kpc supernovae, but can only constrain extreme models for 10 kpc supernovae

HALO 2 the larger the number of counts, the greater the yield for the discriminatory power

Acknowledgements

K.Scholberg, C.Walter, A.Himmel, Duke University High Energy Physics Neutrino Group

Triangle Universities Nuclear Laboratory's Research Experience for Undergraduates

Halo Collaboration/SNOLab