Hyper-Kamiokande project and R&D status
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Transcript of Hyper-Kamiokande project and R&D status
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Jan.-2002 @CERN
Hyper-Kamiokande project andR&D status
Hyper-K project Motivation Detector Physics potential study photo-sensor development
Summary
Kamioka Observatory Masato ShiozawaFor JHF-Kamioka νworking group
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Jan.-2002 @CERN
Super-K has not found nucleon decays in 3.5 years data τ/B(p→e+π0) > 5.0 × 1033 years (90% CL) τ/B(p→ν K+) > 1.9 × 1033 years (90% CL)Predicted lifetime of nucleon 4 fermion interactions
2 fermion – 2 sfermion interactions (SUSY models)
One or two order of extension of Super-Kamiokande would reveal new physics!!!
Next generation proton decay detector
g4 mp4
Γ = : τ(p→e+π0) = 1035±1 years MX
4
h 4 mp4 ____
Γ = : τ(p→K+ν) = 1029-35 years MHx
2 MX2
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Jan.-2002 @CERN
Same baseline with Super-K (295km)
Enable higher statistics physics (22.5 kton ~1000 kton) improved sensitivity for θ13 measurement CP phase measurement in lepton sector test of the unitarity triangle
Detector requirementgood e/π0 separation capability at low energyNo magnetic field is needed
Hyper-K as a far detector of 2nd JHF ν
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Jan.-2002 @CERN
R&D Items for Hyper-K
• cavity design and assessment• rock stress analysis• excavation cost, time, optimization
• physics potential study• optimization of photo-coverage, detector volume• sensitivity for pepi0, nuK+, background estimation• SN, atmospheric nu, and others• long baseline experiment(JHF), pi0 rejection etc.
• photo-sensor development• low cost, high sensitivity• mass production rate automated production• high pressure resistant
• other detector improvement• longer light attenuation length?• reducing reflection light?
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Jan.-2002 @CERNPossible Design of Hyper-Kamiokande
Super-K
40m
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Jan.-2002 @CERNPossible Design of Hyper-Kamiokande (2)
PMT Wall 45m 45m 2 planes 16 modules = 64,800 m2
45m 46m 4 planes 4 modules = 33,120 m2 45m 47m 4 planes 12 modules = 101,520 m2
Total 199,440 m2
200,000 PMTs if 1 PMT/m2 Fiducial Volume 41m 41m 42m 4 modules = 282,408 m3
41m 41m 43m 12 modules = 867,396 m3
Total 1,149,804 m3
2.5 m2 m
3 m
45m45m46m
41m41m42m
45m45m47m
41m41m43m
Total 800m 16 compartments
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Jan.-2002 @CERNPossible Design of Hyper-Kamiokande (3)
#compartments
Total volume
Fiducial volume
PMT density #PMT
Case1 8 1Mton
0.57Mton
1PMT/m2 100k
Case2 8 1Mton
0.57Mton
2PMT/m2 200k
Case3 16 2Mton
1.15Mton
1PMT/m2 200k
Case4 16 2Mton
1.15Mton
2PMT/m2 400k• PMT density should be optimized by
• gamma tagging in nuK+ search, pi0 rejection in long baseline experiment• detector volume should be optimized by
• physics goals• site, stable cavity design• excavation cost, construction time• photo-sensor cost, production time
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Jan.-2002 @CERN
Detector site candidate
Super-K
KAMLAND
Mozumi site Tochibora site
Super-K
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Jan.-2002 @CERN
Analysis for discovery of p→e+π0
Tight momentum cut ⇒ target is mainly free protons efficiency=17.4%, 0.15BG/Mtyr
No Fermi momentumNo binding energyNo nuclear effect
Small systematic uncertainty of efficiency High detection efficiency Perfectly known proton mass and momentum
free proton bound proton
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Lif
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ith
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σ(9
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→ ~
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life
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e
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Jan.-2002 @CERN
How the signal looks like
τp/B(p→e+π0) = 1×1035 years
S/N = 4 for 1×1035 years ↓ S/N = 1 for 4×1035 yearsτp/B(p→e+π0) = several×1035 yrs
is reachable by a large water Cherenkov detector
Proton mass peak can be observed !
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Jan.-2002 @CERN
2. K+ production by atmν νN → νN* ΛK+
~ 1 events/Mtyr (after pdecay cut)
Backgrounds in p→νK+ searches
1. prompt γ ~ 6 events/Mtyr most are misfitted vertex events μ spectram 2100 events/Mtyr (single-ring μ,π,proton) π+π0 ~ 22 events/Mtyr
we should reject them by improved vertex fitter
very serious backgrounds if both Λ and K+ are invisible
K.KobayashiK.Kobayashi
3. other unknown background?
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Lif
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BG
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σ(9
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→ ~
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103
4 ye
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Pro
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Jan.-2002 @CERN
Photo-sensor development
• improving QE• optimizing cathode materials, production methods
• larger (30-40inch) PMTs• glass valve production is a key
• hybrid photo-detector (HPD)• photo-cathode + AD(avalanche diode)• simple structure hopefully low cost• good timing resolution ( ~ 1ns)• good single p.e. separation
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Jan.-2002 @CERN
5 inch HPD prototype
5in
ch
sensi
tive a
rea 8
0m
mφ
e
APD 3mmφ, GNDbias voltage 150V
photo-cathode –8kV
100% coll. efficiency cathode 80mmφ -------- 3mmcathode 120mmφ -------- >10mm
• need higher voltage• larger AD• spherical cathode
electron bombarded gain 1000 ×avalanche gain 50 = 50,000
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Jan.-2002 @CERN
5 inch HPD prototype (2)
measured quantum efficiency time response
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Jan.-2002 @CERN
5 inch HPD prototype (3)
pulse height distribution (dark current)
• good single p.e. peak• dark rate is 24kHz
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Jan.-2002 @CERN
5 inch HPD prototype (4)
(a) cathode uniformity
(b) anode uniformity
geomagnetic effect is seen
need higher voltageand/or larger AD
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Jan.-2002 @CERN
Spherical HPD
glass photocathode
reflector
diode-1
diode-2
light
photoelectrons
Lead and support
• high efficiency• simple structure low cost high production rate• pressure resistant
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Jan.-2002 @CERN
to do list for the new photo-sensor
• gain up
1000(E.B.gain)×50(Av. gain)= 5×104 1×107
• good focusing higher voltage, spherical shape
• good control of AD position
• operation of AD in positive high voltage
• keep low dark rate
• pressure resistant (spherical shape)
• larger size
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Jan.-2002 @CERN
Summary of Hyper-K
Rich physics potential τp/B(p→e+π0) ~ 1×1035 years (3σ CL with
20Mtyr) τp/B(p→ν K+) ~ 3×1034 years (3σ CL with 20Mtyr) Atmospheric, Supernova other physics 2nd phase of JHF-Kamioka neutrino experiment
R&D’s are in progress new photo-sensor