HALO Helium And Lead Observatory

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HALOHelium And Lead Observatory

• SNOLab Workshop III
• Thursday, May 13th
• Laurentian University
• Sudbury

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Overview

• HALO Description and (history)
• Supernovae, Neutrinos and Lead
• Neutrons and NCDs
• Simulations
• Signal and Backgrounds
• Budget
• Conclusion

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HALO?A low-cost supernova detector

• HALO Phase I
• 90 Tons of lead
• From Deep River Cosmic Ray Station, c. 1960
• 200m surplus SNO proportional counters (NCD)
• Moderator
• Reflectors
• Electronics
• Computer

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100kg Lead Bricks from muon counters
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Neutrinos from supernovae

• Neutrinos leaving star are expected to be in a
  Fermi-Dirac distribution according to escape
  depth
• Oscillations redistribute neutrino temperatures
• SK, Kamland are primarily sensitive to ?e

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Expected signal from Supernova Neutrinos

• In 90 tons of lead for a SN _at_ 10kpc,
• Assuming LMA, FD distribution around T8 MeV for
  ?µs, ?ts.
• 76 neutrons through ?e charged current channels
• 34 single neutrons
• 21 double neutrons (42 total)
• 24 Neutrons through ?x neutral current channels
• 10 single neutrons
• 7 double neutrons (14 total)
• 100 neutrons liberated

- Engel, McLaughlin, Volpe, Phys. Rev. D 67,
013005 (2003)
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Neutron spectrum in lead
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HALO Monte CarloWork done by F. Fleurot and J.
Massicotte

• Determines neutron detection efficiency
• Uses GEANT4
• Explores various detector geometries
• Optimizes moderator thickness
• Sets minimum reflector thickness

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Two sample geometries
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NCD Energy Spectrum
764-keV peak
Energy spectrum from one NCD string with an AmBe
neutron source.
191-keV shoulder from proton going into the wall
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Energy vs Duration
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Signal Summary
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HALO Backgrounds

• Norite (a,n) neutrons
• 0.1(e) Hz
• Internal alphas in n-region
• 3.5x10-4 HzLength/200m
• Cosmic ray neutrons
• 1.3x10-5(e) Hz
• Multi-neutron bursts thermalize in 200ms
• Gamma Backgrounds
• lt 1x10-5 Hz

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SNOLAB Requirements

• 3x3x3m cube for optimum efficiency
• Other configurations are possible
• Hallway would be optimum for future expansions
• Overhead crane for setup and movement
• UPS power and remote access for 100 livetime
• Earliest possible start date

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Summary

• HALO is ready to assemble
• Most materials already in Sudbury
• Most hardware already tested and characterized
• Small, adjustable footprint
• Provides information about SN neutrino spectra
• Can easily work with SNEWS for SN watch
• Is readily expandable (new materials/methods)
• Long-term low-upkeep project

• HALO is ready to assemble
• Most materials already in Sudbury
• Most hardware already tested and characterized
• Small, adjustable footprint
• Provides information about SN neutrino spectra
• Can easily work with SNEWS for SN watch
• Is readily expandable (new materials/methods)
• Long-term low-upkeep project

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Collaboration Members as of 5/04

• University of Washingon
• Peter Doe, Charles Duba, Joe Formaggio, Hamish
  Robertson, John Wilkerson
• Laurentian University
• Jacques Farine, Clarence Virtue, Fabrice Fleurot,
  Doug Hallman, Steven Rayan
• Los Alamos National Laboratory
• Jaret Heise, Andrew Hime
• Lawrence Berkeley National Laboratory
• Kevin Lesko
• Carleton University
• Cliff Hargrove, David Sinclair
• Queens University
• Fraser Duncan, Tony Noble