Efficiency and Sensitivity for the HALO Detector

1. Efficiency and Sensitivity for the HALO Detector Cara Esposito Saint Joseph’s University Dr. Kate Scholberg Duke University

2. Outline • Brief background on neutrinos, supernovae, and the HALO detector • Efficiency and the important information gained from examining the efficiency • Sensitivity for HALO • Summary

3. 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

4. Background Before After • Supernovae happen when a massive star can no longer sustain itself and it explodes • 99% of the energy of core collapse supernovae is neutrinos

5. 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 Lead Helium Detectors

6. Background • Visualization of the simulation using Geant4

7. How HALO Works ν ___ ___ ___ ___

8. How HALO Works ν ___ ___ ___ ___

9. How HALO Works ν ___ ___ ___ ___

10. How HALO Works ν ___ ___ ___ ___

11. How HALO Works • 1n ν ___ ___ n ___ ___

12. How HALO Works • 1n ν ___ ___ n ___ ___

13. How HALO Works • 1n ν ___ ___ n n ___ ___

14. How HALO Works • 1n ν ___ ___ n n ___ ___

15. Flux • The left panel is for inverted mass hierarchy • The right panel is for normal mass hierarchy

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

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

18. Efficiency • Tells us how well the detector works

19. 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

20. Sensitivity • For 10 kpc supernovae HALO 1 can only constrain extreme models

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

22. 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

23. 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