Non-Accelerator Physics with the Homestake

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Non-Accelerator Physics with the Homestake
Megaton Array

• 1) Nucleon Decay P? ?o e, P ? K ??e
• (improved PMTs may permit spatial time
  recognition of K ??e)
• 2) Prompt SN neutrinos our Galaxy and nearby
  galaxies
• 3) Relic SN neutrinos (greater depth provides
  critical C.R. muon background reduction)
• 4) Low background shield
• (Used Hank Sobel talk-Korea 2005 Ed Kearns talk
  -NNN07)

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Various Detection Techniques
Free Protons Nuclei Features
Water 11 89 Cerenkov radiation
Liquid Scintillator Could insert into center of 100 kton water detector 10 90 Signal from slow particles
Liquid Argon 0 100 Tracking
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Detector Location Constraints

• 1) Depth
• 2) Distance from Power Reactors
• Lead, SD is 500 km from nearby U.S. power
  reactors factor 30 (1/r2) better than Kamioka
  location

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Vertex Reconstruction of Events

• PMT times used to reconstruct event position
• Resolution 15 cm

UNTAGGED
TAGGED
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Large Format PMTs
20 inch
For Better Detection Efficiency
13 inch PMT is very low profile despite its
diameter.
R3600
13 inch
10 inch
8 inch
R8055
R7081
R5912

• Applications
• Neutrino Experiment

Trial for High QE
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Hamamatsu PMT Characteristics
PMT Dia. Quantum Efficiency Rise Time Transit time jitter
3600 20 20 10 ns 5.5 ns
7081 10.5 gt35 4.3 ns 2.9 ns
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Bialkali QE Comparison
UBA43
Example Data for UBA R7600-200 SBA
R7600-100 STD R7600
x1.6
x1.3
SBA35
STD26
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Example data R7081 (10 inch)
High QE Type Champion Data 35 at 380 nm
Samples22 pcs Average31.6
Standard 26 at 380 nm
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