1. Detecting Supernova Neutrinos at Neutrino Experiments
Shaomin Chen (陈少敏)
Center for High Energy Physics (高能物理研究中心)
Department of Engineering Physics（工程物理系）
Tsinghua University (北京清华大学)
2013年兩岸粒子物理與宇宙學研討會
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2. Outline Introduction Supernova Neutrino Signal
SN Burst neutrinos
SN Relic Neutrinos
SN Neutrino Interactions at Targets
Typical Neutrino Detection Methods
In Water and In Liquid Scintillator
Background sources
Status & Outlook
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3. Introduction
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4. SN1987a First observation came from optical instruments.
Before February 23, 1987
After February 23, 1987
First observation came from optical instruments.
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5. SN1987a Neutrino Detections
2140-ton pure water
Time accuracy  1 s
Threshold: 5 MeV
6800-ton pure water
Time accuracy  50ms
Threshold 5 MeV
w/ ¼ PMT HV off
200-ton LS
Time accuracy +2/-54 s
Later confirmed by the neutrino experiments.
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6. 2002 Nobel Prize in Physics
"for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos"
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7. Puzzles in Measurements
“One puzzling feature of the SN 1987a data is that the neutrinos detected by the IMB detector were seemingly more energetic than those detected by the Kam-II detector, which were clustered at low energies.”
Phys.Rev. D76 (2007)
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8. Classification of SN Neutrinos
John Beacom, TAUP2011
DSNB=Diffuse Supernova Neutrino Background
But we prefer to call them Supernova Relic Neutrinos
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9. Supernova Neutrino Signal
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10. Model for Core-Collapse SN
Stage 3, 4, 5 are expected to be distinguished by the SN neutrino time spectra.
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11. SN Neutrino Time Spectra
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12. Time Structures in N and <E>
T.Totani, K.Sato, H.E.Dalhed and J.R.Wilson, ApJ.496,216(1998)
Model based on SN1987a.
Special time structure.
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13. SN Neutrinos As Probes of MH
The original flavor at emission arriving at a detector on Earth depends on the neutrino mass hierarchy.
C.D. Ott, et al., arXiv:
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14. Expected SN Rate per Century
SN burst neutrinos expected from
Type Ib, Ic and Type II SNe.
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15. Galactic SN Distance
Mirizzi, et al. astro-ph/
If a detector is sensitive up to 20kpc, it covers 97% of our galaxy.
Core collapse type
mean: 10.7 kpc
r.m.s.: 4.9 kpc
16% probability
< 5 kpc
Type Ia
7% probability
< 3.16 kpc
3% probability
> 20 kpc
10kpc
20kpc
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16. Candidate SN Close to Us
Eta Carinae：2.3kpc to the Earth (SN1987a为52±5 kpc),with a mass equivalent to Suns. Near the same bright as normal SNs, predicted to be the next SN or Hyper SN.
Betelgeuse：
0.2kpc to the earth, with a
Mass equivalent to
18-19 Suns. The brightest
one in the sky if our eyes
can see all the wavelength.
SN1987a
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17. Supernova Relic Neutrinos
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18. SK
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19. SN Neutrino Interactions at Targets
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20. SN Neutrino Interactions in Use
Inverse Beta Decay
Elastic Scattering On Electrons
CC and NC Interactions With Nuclei
Coherent Elastic Neutrino-Nucleus Scattering
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21. 2019/4/28

22. Typical Neutrino Detection Method
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23. Detection in Water n g ne p p Gd e+ g
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24. Particle ID at SK Ring pattern diff. used for PID If +/– is fully
contained in the
inner tank
Cone vertex and
# of PMT and total
charge collected used
for measuring Evis
Ring pattern diff.
used for PID
If e+/e– is fully
contained in the
inner tank
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25. Detection in Liquid Scintillator n n e t
A prompt event correlated with a delayed event
Isotropic scintillation light
Typical a 8 MeV gamma cascade and a 2.2 MeV gamma
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26. Summary of SN Experiments
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27. Background in SN Burst Neutrinos
Signal
Background
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28. Spallation Background
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29. Background Sources in SRN
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30. Status and outlook
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31. Expected SN Neutrino Events
Kamioande
Daya Bay
参宿四
（0.2kpc）
海山二
（2.3kpc）
1987a
（51.4kpc）
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32. SuperNova Early Warning System
Individual SN-sensitive experiments send burst datagram to SNEWS coincidence computer at BNL to alert astronomers if coincidence in 10 s
Participating experiments:
Large
Volume
Detector
(Italy)
Super-
Kamiokande
(Japan)
AMANDA/
IceCube
(South Pole)
SNO
(Canada)
until end of 2006
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33. (S. Chen and Z.Deng) Nucl. Phys. Proc. Suppl. 166:252,2006SK
2.2MeV g-ray
DT = ~ 200 msec
Forced Trigger
n+p→d + g
# of hit PMT’s ~ 6 n g ne p p Gd
(S. Chen and Z.Deng) Nucl. Phys. Proc. Suppl. 166:252,2006 e+ g
n+Gd →~8MeV g’s
DT = ~30 msec
GADZOOKS!
(J.Beacom and M.Vagins) Phys.Rev.Lett.93:171101,2004
Add 0.2% GdCl3 in water
ne can be identified by delayed coincidence.
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34. Water with 0.2% GdCl3 Solution
5 cm
Am/Be
α + 9Be → 12C* + n
12C* → 12C + g(4.4 MeV)
n + p → …… → n + Gd → Gd + g (totally 8 MeV)
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35. The 8 MeV Gamma Cascade @SK
Efficiency ~ 67%
Background probability ~ 2 x 10-4
Distance to positron [cm]
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36. The 2.2 MeV SK
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37. Efficiency & BKG Prob. Efficiency ~ 18%
Background probability ~ 1 x 10-2
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38. 2.2 MeV Gamma in Neutrino Data
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39. A First Look Into SK-IV Data
KamLand
SK-IV
SK-I+II+III
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40. Prospect of SRN at SK Assuming ~70% efficiency. By 10 yrs SK data,
Assuming invisible muon B.G. can be reduced by a factor of 5 by neutron tagging.
Assuming
~70% efficiency.
By 10 yrs SK data,
Signal: 33, B.G. 27
(Evis =10-30 MeV)
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41. SN Burst Neutrinos @DayaBay
4x(20+20)+2x(20+20)+
2x(20+20)=320 tons
Three-hall configuration can significantly reduce false SN alarming by the spallation background
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42. SN Neutrinos at DayaBay-II
20k ton LS
DYB
DYB II
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43. 阳江 台山
Status
Under construction
Power
17.4 GW
18.4 GW
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44. Outlook Many Physics in SN Neutrinos
Dynamics of Core-Collapse SN, Mass Hierarchy
Star Formation History, …
Rare SN burst neutrinos but copious SRNs
Need large volume of target mass with advanced detection technologies
A more realistic outlook
SK with Gd+H and Daya Bay II
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45. THANKS!
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