Status of the SNO+ experiment Richie Bonventre for the SNO+ - - PowerPoint PPT Presentation

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Status of the SNO+ experiment Richie Bonventre for the SNO+ - - PowerPoint PPT Presentation

Oct 23, 2023 390 likes •534 views

Status of the SNO+ experiment Richie Bonventre for the SNO+ collaboration WIN 2017 Lawrence Berkeley National Lab The SNO+ collaboration University of Alberta Armstrong Atlantic State University University of California, Berkeley /

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SLIDE 1

Status of the SNO+ experiment

Richie Bonventre for the SNO+ collaboration WIN 2017

Lawrence Berkeley National Lab

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SLIDE 2

The SNO+ collaboration

120 members of 23 institutions over 6 countries

  • University of Alberta
  • Armstrong Atlantic State University
  • University of California, Berkeley / LBNL
  • Black Hills State University
  • Brookhaven National Laboratory
  • University of California, Davis
  • University of Chicago
  • Technical University of Dresden
  • Lancaster University
  • Laurentian University
  • LIP Lisboa and Coimbra
  • University of Liverpool
  • University of North Carolina at Chapel Hill
  • Oxford University
  • University of Pennsylvania
  • Queen Mary University of London
  • Queen’s University
  • SNOLAB
  • University of Sussex
  • TRIUMF
  • Universidad Nacional Autonoma de Mexico
  • University of Washington

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SLIDE 3

The SNO detector

  • 2km underground, 6010 mwe
  • ∼63 cosmic muons per day
  • Support structure holding ∼9300

PMTs (∼50% coverage)

  • 7 kT ultra pure water shielding
  • Target volume contained in 6m

radius acrylic vessel

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SLIDE 4

The SNO detector → SNO+ detector

SNO+ detector upgraded to look for neutrinoless double beta decay

  • Target material changing from

heavy water to liquid scintillator

  • Lower energy threshold and higher

resolution

  • Load with 130Te for 0νββ

measurement

  • Hold-down ropes: compensate for

buoyancy of scintillator

  • Upgraded electronics: handle

higher event rates (>1kHz)

  • Repaired PMTs
  • Installed new LED calibration

system

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SLIDE 5

Liquid scintillator + Tellurium

  • Scintillator: Linear Alkylbenzene
  • High light yield (∼1000 photons/MeV)
  • Long attenuation length (∼20 m)
  • High flash point (safe)
  • Wavelength shifter: PPO
  • x10 light yield
  • α/β discrimination
  • Double beta decay isotope: 130Te
  • Long 2νββ lifetime: ∼7x1020 yrs
  • High Q value ∼2.5 MeV
  • High natural abundance
  • No absorption lines in PMT sensitive

region

  • Plan for 0.5% loading with

Te-butanediol (∼1330 kg of 130Te)

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SLIDE 6

Double beta decay signals and backgrounds

  • ∼13 counts/year

backgrounds in first year

  • Expected spectrum after full 5 year run with

0.5% loading, with mββ = 200meV

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SLIDE 7

Double beta decay sensitivity

Live time (y) 1 2 3 4 5 6 7 8 9 10 (y) sensitivity

ν 1/2

T

26

10

  • Phase I:
  • T1/2 ∼ 2 × 1026 years
  • Phase II: Increased Te loading, HQE PMTs

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SLIDE 8

Other physics with SNO+

Water Phase Pure Scintillator Phase Te-loaded Scintillator Phase Neutrinoless double beta decay ×

8B solar neutrinos

× × Low energy solar neutrinos × Reactor and geo neutrinos × × Exotics searches (ex.: nucleon decay) × × × Supernova × × × 7 / 13

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SLIDE 9

Nucleon decay

Energy (MeV) 1 2 3 4 5 6 7 8 9 10 Events per year per 0.2 MeV 10−1 1 10 102 103 104 p decay (2.1 × 1029 yr) n decay (5.8 × 1029 yr) Solar ν Internal 214Bi Internal 208Tl Reactor ¯ ν External 214Bi + 208Tl

  • Look for invisible decay, e.g.: n → ννν
  • 16O →15O∗ or 15N∗, ∼ 5 MeV visible energy
  • 6 months of data → 30 background counts in ROI
  • 90% CL:
  • τn=1.2x1030 years (current limit KamLAND: 5.8x1029)
  • τp=1.4x1030 years (current limit SNO: 2.1x1029)

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SLIDE 10

Upgrades and commissioning progress

  • Repaired leaks in cavity and replaced

repaired PMTs

  • LED/Laser calibration system installed
  • Hold down ropes installed - buoyancy

test carried out over several periods of water filling

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SLIDE 11

Upgrades and commissioning progress

  • Scintillation plant installed and being

commissioned

  • LAB shipments underground started
  • TeA stored underground
  • Tellurium purification plant construction

started

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SLIDE 12

Upgrades and commissioning progress

  • Upgraded electronics and DAQ tested at

high data and trigger rates

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SLIDE 13

Current Status

  • Inner and outer volumes

filled with water

  • Laser and 16N source

calibrations

  • Water phase data taking

has begun

  • Nucleon decay

measurement

  • Characterize external

backgrounds for future phases

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SLIDE 14

Conclusion

Candidate atmospheric neutrino event

  • SNO+ is currently filled with water and taking physics data
  • In 6 months of running it will provide the strongest limit on invisible

nucleon decay

  • Scintillator purification system being commissioned
  • Tellurium systems under construction
  • Neutrinoless double beta decay phase will begin in 2018
  • In 5 years will reach the top of the inverted hierarchy

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