Prospect for detection of supernova neutrino
NOW2014
Sep. 9th, 2014
Otranto, Lecce, Italy
森俊彰 Takaaki Mori
for the Super-Kamiokande Collaboration
Okayama University, Japan
Contents
• Supernova burst neutrinos• Supernova relic neutrinos
• GADZOOKS!
• Pre-supernova neutrinos
3
Neutrino from supernova• A supernova explosion happens
when a star at least 8 times more massive than the sun collapses.
• Released gravitational energy: ~3x1053 erg. Neutrinos carry almost all (99%) of the energy.
• Supernova neutrinos detection provides a lot of information– Collapse physics– Neutrino Physics
• Detection of SN neutrino is very importantLivermore simulation:
APJ, 496, 216 (1998)
Luminosity
Average E
Supernova burst detectors in the world(running and near future underground experiments)
Super-K
KamLAND
BaksanLVD Borexino
SNO+
(under construction)
IceCube
HALO
Detectors on surface likeNOvA (14kton liquid scintillator(LS)),Daya Bay (160ton Gd-doped LS)can also be supernova detectors.
5
Super-Kamiokande
• 32 kton water Cherenkov detector• Dominant interaction is IBD (ne+p)
( ~7300 events in total ~8000 events for 10kpc SN)– Enough statistics to discuss model predictions
• Good directionality for ne scattering (~300 events)
• SN monitor is running 24 hours a day
• Announce the SN neutrino detection and its direction to the world within an hour
6
IceCube
• High statistics– 0.75% stat. error
@ 0.5 sec and 100 ms bins
[sec] From L.Koepke
• ~kilometer long strings of PMTs in clear ice
• Although multi-GeV energy threshold, may see burst as coincident increase in single PMT count rate
• Cannot tag flavor, or other event-by-event info, but map overall burst time structure
7
Liquid scintillator detectors
Expected number of events for 10 kpc SN• Inverse beta : ~300 events/kton
– Spectrum measurement with good energy resolution
• CC on 12C : ~ 30 events/kton
• Electron scattering : ~20 events/kton
• NC g from 12C : ~60 events/kton– Total neutrino flux,
15.11 MeV mono energetic g
• n + p NC : ~ 300 events/kton– Sensitive to all types of neutrinos
( Independent from neutrino osc.)
From K.Inoue, G.Belliini, M.Chen
Spectrum @KamLAND
(Flux:PRD67,023004 (2003))
Supernova Relic Neutrino
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Supernova Relic Neutrino
• In the Universe, there exist SRN emitted from the past supernovae explosion
• Expected SRN events : 1.3~6.7 events/year/22.5kton ( 10-30 MeV )• Large target mass and high background reduction are necessary
Time
SRN predictions(ne fluxes)
Neu
trin
o flu
x (/
cm2 /
sec/
MeV
) SRN mode : PRD, 79, 083013 (2009)
Neutrino Energy[ MeV]
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SRN search at Super-K
e+
proton
g
ne
neutron
proton
2.2 MeV g(Not efficiently detected)
• Search for SRN is limited by background– Need to identify neutron to
suppress the atmospheric neutrino background
K.Bays et al.,PRD85(2012)
dataνμ CCνe CCNC elasticμ/π > C. thr.all backgroundSRN
25 50 75Energy [MeV]
• Super-K has the best sensitivity to the SRN via IBD interaction– flux<2.9 ne (1/cm2/sec)
GADZOOKS! Beacom and Vagins PRL93,171101 (2004)
(Gadolinium Antineutrino Detector Zealously Outperforming Old Kamiokande, Super!)
• Large cross section for thermal neutron (~ 90% @ 0.1 % Gd)
• Neutron captured Gd emits 3-4 g ray in total 8 MeV
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e+
proton
gne
neutron
Gd
SRN mode:PRD79,083013(2009)
12
SN n detection w/ neutron tagging
SN @ 10 kpc
Direction of SN can be determined with an accuracy of ~ 5 deg. ->By neutron tagging, direction accuracy can be improved to ~3 deg.
Flux and spectrum : Livermore simulation
13
• Item to study with EGADS– Effect to Water transparency– Water purification system– Neutron detection efficiency– Etc.
EGADS experiment(Evaluating Gadolinium’s Action on Detector System)
14
“Selective filtration system”
(Water purification system)
UDEAL
(Water Transparency measurement device)
200 m3 detector
(240 photo sensor)
15 m3 tank and pre-treatment system
15
Current status of EGADS
Step1
• Circulation with pure water
Step2
• Circulation with Gd-doped water
Step3
• PMT installation
step4
• Circulation with pure water• Detector calibration
step5
• Circulation with Gd-doped water • Data taking
Step6
• Refurbish• Data analysis
step7
• Circulation with Gd-doped water• Evaluation of GADZOOKS!
←achieve same level pure water transparency
←achieve 86.2% of pure water cases
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Current status of EGADS
Step1
• Circulation with pure water
Step2
• Circulation with Gd-doped water
Step3
• PMT installation
step4
• Circulation with pure water• Detector calibration
step5
• Circulation with Gd-doped water • Data taking
Step6
• Refurbish• Data analysis
step7
• Circulation with Gd-doped water• Evaluation of GADZOOKS!
17
Current status of EGADS
Step1
• Circulation with pure water
Step2
• Circulation with Gd-doped water
Step3
• PMT installation
step4
• Circulation with pure water• Detector calibration
step5
• Circulation with Gd-doped water • Data taking
Step6
• Refurbish• Data analysis
step7
• Circulation with Gd-doped water• Evaluation of GADZOOKS!
18
Current status of EGADS
Step1
• Circulation with pure water
Step2
• Circulation with Gd-doped water
Step3
• PMT installation
step4
• Circulation with pure water• Detector calibration
step5
• Circulation with Gd-doped water • Data taking
Step6
• Refurbish• Data analysis
step7
• Circulation with Gd-doped water• Evaluation of GADZOOKS!
←we found bad material, which is not used in SK detector
19
Current status of EGADS
Step1
• Circulation with pure water
Step2
• Circulation with Gd-doped water
Step3
• PMT installation
step4
• Circulation with pure water• Detector calibration
step5
• Circulation with Gd-doped water • Data taking
Step6
• Refurbish• Data analysis
step7
• Circulation with Gd-doped water• Evaluation of GADZOOKS!
20
Transparency of Gd-doped waterw/o PMT
60
65
70
75
80
85
90
Che
renk
ov li
ght
left
( %
)
BGO
Am/Be
Measurement of Gd g
DT[ms]Total electron Energy[MeV]
Eve
nts
/ #
of p
rom
pt t
rg.
Eve
nts
/ # o
f pro
mpt
trg.
241Am → 237Np + a
9Be + a→ 12C + g(4.4MeV)+ n
Gd g
Gate : 500msec
Delayed signal
Prompt signalScintillation
Gd2(SO4)3 concentration: 200 ppm
Pre-supernova neutrino detection
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Pre-supernova neutrinos
• Importance of detection– Investigation of mechanism of evolution
of star at final at stage and collapse– Alarm before the SN neutrino burst
• Target– Antares (~170pc)– Betelgeuse (~150pc)– Gamma Velorum (~340pc)
ACTA PHYSICAL POLONOCA B 40, 3063 (2009)
Shell Si starts
Core Si burning
Direct pre-collapse stage
Shock breakout
SN neutrino burst
Log
L n [
erg/
s]
Neutrino is emitted in Si burning phase before core-collapse supernova
24
Pre-SN neutrino detection @ KamLAND
Expected number of events @KamLAND
The early alarm will be issued from 3 days to 5 hours before from core-collapse
Significance
Normal hierarchy
Inverted hierarchy
Flu
x@1p
c(10
6 /cm
2 /s/
MeV
)
Anti ne energy [ MeV ]
From K.Ishidoshiro
Time[day]
Reactor + spallation
Betelgeuse@GADZOOKS!
Pre-SN neutrino detection by GADZOOKS!
Like KamLAND, SK(GADZOOKS) will try for a very early alarm
• In case of Betelgeuse assuming distance is 0.13 kpc
# of only neutron signals in IBD interaction
A.Odrzywolek et al., AIP Conf. Proc. 944, 109 (2007)
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Summary
• Supernova burst neutrinos• SN neutrino provides a lot of information by energy,
flavor, timing..• Many detectors are waiting a SN burst
• Supernova relic neutrinos• R&D project for GADZOOKS! is ongoing
• Supernova neutrino at Si burning stage• Its detection provide the very early alarm for supernova
burst• KamLAND and GADZOOKS! can get precursor
backup
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S.Ando, NNN05
Supernova Relic NeutrinosS.Ando, Astrophys.J.607:20-31,2004.
~1017 supernovae so far.
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Super-K
LVD
IceCube
Borexino
snews.bnl.gov
SNEWS: SuperNova Early Warning System
KamLAND
Daya Bay(soon)
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Supernova burst detectors in the world(running and near future underground experiments)
Super-Kamiokande
KamLAND
BaksanLVD
Borexino
SNO+
(under construction)
IceCube
HALO
Detectors on surface likeNOvA (14kton liquid scintillator(LS)),Daya Bay (160ton Gd-doped LS)can also be supernova detectors.
Current Liquid scintillator detectors
KamLAND(1kton)
Borexino(0.33kton)
SNO+ (1kton)
under construction
LVD(1kton)
NOnA(14kton)
alert to astronomers
experimentUT timesignificance 10 second
coincidenceby UT time stamp
Coincidence Server at BNL
SNEWS: SuperNova Early Warning System- Neutrinos (and GW) precede em radiation by hours or even days- For promptness, require coincidence to suppress false alerts
- Running smoothly for more than 10 years, automated since 2005 - Amateur astronomer connection
snews.bnl.gov
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UDEAL
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Pre-treat system
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Gd removal system
43
v
Supernova burst detectors in the world(running and near future underground experiments)
Super-K
KamLAND
BaksanLVD Borexino
SNO+
(under construction)
IceCube
HALO
76 ton Pb, 3He counter~ 40 ev.
1 kton liq.sci.~ 300 ev.
0.3 kton liq.sci.~ 100 ev.
Giant ice
1 kton liq.sci.~ 300 ev.
32 kton water ~ 8000 ev.Good directionality
0.33 kton liq.sci.~ 100 ev.
1 kton liq.sci.~ 300 ev.
# of expected ev. for 10 kpc
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Pre-supernova neutrino
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