prospect for detection of supernova neutrino now2014 sep. 9 th, 2014 otranto, lecce, italy 森俊彰...

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]

10

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)

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“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)

32

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

40

Pre-treat system

41

42

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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46

Pre-supernova neutrino