1. Supernova neutrino detection
Kate Scholberg, Duke University
Neutrino Champagne 2009

2. OUTLINE Neutrinos from supernovae Supernova neutrino detection
Inverse beta decay
Other CC interactions
NC interactions
Summary of current and near future detectors
Farther future detectors
Extra galactic neutrinos
Relic neutrinos
Pointing to a supernova with neutrinos
Summary 

3. What We Can Learn CORE COLLAPSE PHYSICS
explosion mechanism
proto nstar cooling, quark matter
black hole formation
accretion disks
nucleosynthesis
from flavor,
energy, time
structure
of burst
NEUTRINO/OTHER PARTICLE PHYSICS
n absolute mass (not competitive)
n mixing from spectra: flavor conversion in SN/Earth
(' q13 the lucky and patient way' )
other n properties: sterile n's, magnetic moment,...
axions, extra dimensions, FCNC, ...
+ EARLY ALERT

4. What do we want in a SN n detector?
- Need ~ 1kton for ~ few 100 interactions for
burst at the Galactic center (8.5 kpc away)
- Must have bg rate << rate in ~10 sec burst
(typically easy for underground detectors,
even thinkable at the surface)
Also want:
Timing
Energy resolution
Pointing
Require NC sensitivity
for nm,t , since SN n
energies below
CC threshold
Flavor sensitivity
Sensitivity to different flavors
and ability to tag interactions is key!
ne vs ne vs nx

5. g g e+ ne + p  e+ + n ne Good old CC inverse beta decay ,
the workhorse of neutrino physics,
serves us well for SN neutrino detection: g e+ n
2.2 MeV
0.511 MeV ne g
Inverse Beta Decay (CC)
ne + p  e+ + n
Can often exploit delayed (~180 ms)
coincidence of n + p  d + g
(or other neutron capture) as tag
(also possibly g's from e+ annihilation)
In any detector with lots of free protons (e.g. water, scint)
this dominates by orders of magnitude

6. WATER CHERENKOV DETECTORS
Volume of clear water
viewed by PMTs
- few 100 events/kton
- typical energy threshold
~ several MeV makes
2.2 MeV neutron tag difficult
Super-Kamiokande IV
22.5 kton f.v.:
~8000 inverse beta
decay 10 kpc

7. Possible enhancement:
use gadolinium to capture neutrons for tag of ne
ne + p e+ + n
Gd has a huge n capture cross-section:
49,000 barns, vs 0.3 b for free protons;
n + Gd  Gd*  Gd + g
Previously used in small scintillator detectors;
may be possible for large water detectors
with Gd compounds in solution
Beacom & Vagins, hep-ph/
R&D is currently underway for SK with half kton test tank in the Kamioka mine

8. LONG STRING WATER CHERENKOV DETECTORS
~kilometer long strings of PMTs
in very clear water or ice
Nominally multi-GeV energy
threshold... but, may see burst of
low energy ne's as coincident
increase in single PMT count
rates (Meff~ 0.4 kton/PMT)
cannot tag flavor,
or other interaction
info, but gives
overall rate and
time structure
IceCube
at the South Pole

9. Few ~ms timing may be possible @ 10 kpc w/IceCube
Halzen & Raffelt, arXiv:
Few ~ms timing may be 10 kpc w/IceCube

10. SCINTILLATION DETECTORS
Liquid scintillator CnH2n
volume surrounded by
photomultipliers
- few 100 events/kton
- low threshold, good neutron
tagging possible
- little pointing capability
(light is ~isotropic)
KamLAND
(Japan)
LVD
(Italy)
Mini-BooNE
(USA)
Borexino
(Italy)
SNO+
(Canada)
(+Cherenkov)
+Double Chooz, Daya Bay and RENO

11. NOnA: long baseline oscillation experiment (Ash River, MN)
15 kton scintillator, near surface
K. Arms, CIPANP ‘09

12. CC interactions on nuclei play a role, too
For most existing (and planned)
large detectors, inverse beta decay dominates,
(and is potentially taggable) so primary sensitivity is to ne
CC interactions on nuclei play a role, too
(cross-sections smaller for bound nucleons)
ne + n  p + e- :
ne + (N,Z)  (N-1, Z+1) + e-
ne + p  n + e+ :
ne + (N, Z)  (N+1, Z-1) + e+
Observables
for tagging
- charged lepton e+/-
- possibly ejected nucleons
- possibly de-excitation g's
depends on
nucleus
Nuclear physics important in understanding cross-sections
and observables!
... often large uncertainties, need to measure!

13. Examples of CC interactions of SN n with nuclei:
Interactions with oxygen in water
ne + 16,18O  16,18F + e-
e.g. Super-K,
~few 8.5 kpc
ne + 16O  16N + e+
Interactions with carbon in scintillator
e.g. LVD, KamLAND,
Borexino
8.5 kpc
ne + 12C 12N + e-
ne + 12C  12B+ e+

14. ICARUS: 600 ton LAr ne + 40Ar  e- + 40K* CC _ ne + 40Ar  e- + 40Cl*
Ethr=1.5 MeV _
ne + 40Ar  e- + 40Cl*
Ethr=7.48 MeV NC
nx + 40Ar  nx + 40Ar*
Ethr=1.46 MeV ES
ne,x + e-  ne,x + e-
Tag modes with gamma
spectrum (or lack thereof)
Excellent electron
neutrino sensitivity

15. HALO at SNOLab ne + 208Pb  208Bi* + e- nx + 208Pb  208Pb* + nx
Relative rates
depend
on n energy
 spectral
sensitivity
(oscillation sensitivity)
ne + 208Pb  208Bi* + e-
CC, Ethr=18 MeV
1n, 2n emission
nx + 208Pb  208Pb* + nx
1n, 2n, g emission NC
from
T. Massicotte
thesis
SNO 3He counters + 76 tons of Pb: ~85 10 kpc

16. Also: elastic scattering (CC and NC contributions)
ne,x + e-  ne,x + e-
In water Cherenkov
and scintillator,
few % of inverse bdk rate
ne,x e-
POINTING from Cherenkov cone:
(degraded by isotropic bg)
Super-K: expect few hundred ES
for 10 kpc SN  ~ 8o pointing
(probably best bet for pointing)
Beacom & Vogel, astro-ph/
Tomas et al., hep-ph/

17. We have sensitivity to electron flavor
neutrinos via CC interactions...
but ~2/3 of the luminosity is m and t flavor;
can be detected via NC interactions only
Typically, signature is nucleon emission
or nuclear de-excitation products
e.g.
nx + (A,Z)  (A-1,Z) + n + nx
nx + (A,Z)  (A,Z)* + nx
sometimes
good tag
is possible
(A,Z) + g
Again, nuclear physics matters!

18. Examples of NC interactions
Interactions with oxygen in water
K. Langanke et al.,
nucl-th/
e.g. Super-K,
~few hundreds
@ 8.5 kpc
nx + 16O  nx + 16O*
16O + g's
Interactions with carbon in scintillator
e.g. LVD,
KamLAND,
Borexino
~few 8.5 kpc
nx + 12 C  nx + 12C*
12C + g
15.11 MeV

19. NC neutrino-proton elastic scattering
nx + p  nx + p
J. Beacom et al., hep-ph/
Recoil energy small, but visible in scintillator
(accounting for 'quenching' )
Recoil spectrum
in KamLAND
Expect ~few 100
events/kton
for 8.5 kpc SN

20. Neutrino-nucleus NC elastic scattering in ultra-low energy detectors
nx + A  nx + A
C. Horowitz et al., astro-ph/
High x-scn but very low recoil energy (10's of keV)
 possibly observable in solar pp/DM detectors
~ few events per ton
for Galactic SN
nx energy information
from recoil spectrum
e.g. Ar, Ne, Xe, Ge, ...
DM detectors,
e.g. CLEAN/DEAP
Spherical Xe TPC
Aune et al.

21. ne + p  e+ + n Summary of SN neutrino detection channels
Inverse beta decay:
- dominates for detectors with lots of free p (water, scint)
- ne sensitivity; good E resolution; well known x-scn;
some tagging, poor pointing
CC interactions with nuclei:
- lower rates, but still useful, ne tagging useful (e.g. LAr)
- cross-sections not always well known
Elastic scattering: few % of invbdk, but point!
NC interactions with nuclei:
- very important for physics, probes m and t flux
- some rate in existing detectors, new observatories
- some tagging; poor E resolution; x-scns not well known
- coherent n-p, n-A scattering in low thresh detectors

22. Current supernova neutrino detectors
Type
Location
Mass
(kton)
Events
@ 8 kpc
Status
Super-K
Water
Japan 32
8000
Running (SK IV)
LVD
Scintillator
Italy 1
300
Running
KamLAND
Borexino
0.3
100
IceCube
Long string
South Pole
0.4/PMT
N/A
Baksan
Russia
0.33 50
Mini-
BOONE
USA
0.7
200
Primary sensitivity is to electron antineutrinos
via inverse beta decay
ne + p e+ + n

23. SNEWS: Supernova Early Warning System
SNO
(until 2006)
LVD
Super-K
AMANDA/
IceCube
Borexino

24. Current and near-future supernova neutrino detectors
Type
Location
Mass
(kton)
Events
@ 8 kpc
Status
Super-K
Water
Japan 32
8000
Running (SK IV)
LVD
Scintillator
Italy 1
300
Running
KamLAND
Borexino
0.3
100
IceCube
Long string
South Pole
0.4/PMT
N/A
Baksan
Russia
0.33 50
Mini-
BOONE
USA
0.7
200
HALO
Lead
Canada
0.076 85
Under construction
Icarus
Liquid argon
0.6
230
Almost ready
NOnA 15
3000
Construction started
SNO+
Funded
Plus: reactor scint detectors, coherent nA scattering detectors, geochemical

25. How far can we look out? SK has farthest reach now
Distant burst search:E 17 MeV, 2 ev/20 s
Low threshold burst search:
E~ 7 MeV,  3 ev/0.5 s OR
 4 ev/2 s OR  8 ev/10 s
Ikeda et al., arXiv:

26. Current best neutrino detectors
sensitive out to ~ few 100 kpc..
mostly just the Milky Way
31 per century

27. Looking beyond: number of sources α D3
S. Ando et al., astro-ph/ SK
Mton
doubles
singles{
With Mton scale detector, probability of detecting 1-2 events
reasonably close to ~1 at distances where rate is <~1/year
Tagging signal over background becomes the issue
⇒ require double n's or grav wave/optical coincidence

28. Next generation mega-detectors (10-20 years)
5-100 kton-scale
LAr detector
concepts
DUSEL
LBNE
10-100
kton-scale
scintillator
detector
concepts
Hyper-K
LENA,
HanoHano
Memphys
Megaton-scale water
detector concepts

29. Zoom in on LBNE water Cherenkov detector Possible WC detector design:
100 kton modules
Studies underway
to optimize
detector
parameters
e.g. PMT coverage,
Gd solute
(for SN, want
low threshold)

30. Expected signal at 7 MeV threshold
SN burst signal
CR m (unvetoed)
other bg, scaled from SK
Clean signal out to Andromeda @ 4290 mwe

31. And going even farther out: we are awash in a
sea of 'relic' or diffuse SN n's (DSNB),
from ancient SNae
8B  flux
hep  flux
atm. e flux
SRN window!
M. Goodman
Learn about star
formation rate,
which can constrain
cosmological models
Difficulty is tagging
for decent signal/bg
(no burst,
2 n coincidences
optical SNae...)
C. Lunardini

32. In water:
ne + p  e+ + n
M. Nakahata, Neutrino 2008 talk
- Worst background is 'invisible muons' below
Cherenkov threshold from atmospheric neutrinos
→ reduce by tagging electron antineutrinos with Gd
- But for a big detector requires low energy threshold ($)
- LAr is also promising (no Cherenkov threshold)

33. more background less background
DSNB Galactic SN
~300 events/kt/30 year
~0.1 event/kt/year
~10 events/kt/yr
more background less background
low rate of return,
but a sure thing
risky in the short term, but you
win in the very long term
bonds vs stocks...
(Of course if you build a big detector and run
it a long time, you may get both! Diversify!)
(But we must remember that no experiment
is ‘too big to fail’... )

34. Summary of supernova neutrino detectors
Type
Location
Mass
(kton)
Events
@ 8 kpc
Status
Super-K
Water
Japan 32
8000
Running (SK IV)
LVD
Scintillator
Italy 1
300
Running
KamLAND
Borexino
0.3
100
IceCube
Long string
South Pole
0.4/PMT
N/A
Baksan
Russia
0.33 50
Mini-
BOONE
USA
0.7
200
HALO
Lead
Canada
0.076 85
Under construction
Icarus
Liquid argon
0.6
230
Almost ready
NOnA 15
3000
Construction started
SNO+
Funded
LBNE LAr 5
1900
Proposed
LBNE WC
78,000
MEMPHYS
Europe
440
120,000
Hyper-K
500
130,000
LENA
15,000
GLACIER
38,000
Galactic sensitivity
Extragalactic

35. LBNE WC / Hyper-K / MEMPHYS: <~ 1o pointing
POINTING to the supernova with future detectors
(should be prompt if possible)
Elastic scattering off electrons is the best bet
In water Cherenkov
few % of total rate
ne,x + e-  ne,x + e-
ne,x e-
G. Raffelt
LBNE WC / Hyper-K / MEMPHYS: <~ 1o pointing
Other possibilities: - time triangulation
- inv. bdk e+n separation
- ~TeV neutrinos (delayed)
Tomas et al.
hep-ph/

36. Another pointing possibility: (if no WC detector running)
Use the matter oscillation energy spectrum to
find the pathlength L traveled in the Earth
(assume parameters favorable, and well known)
KS, A. Burgmeier, R. Wendell
arXiv:
For a known pathlength, the supernova will be
found on a ring on the sky

37. Inverse energy spectrum, L=6000 km Power spectra for different L
A. S. Dighe, et al. hep-ph/
Peak in power
spectrum vs
L for 500,000
simulated SNae,
60,000 events
each (perfect energy resolution)
 measure kpeak to find allowed L values

38. Example skymaps One detector Two detectors Three detectors
Perfect energy resolution
60,000 neutrino events
SN at dec=-60o, RA=20h, 0:00
Finland
Two detectors
Finland+Hawaii
Three detectors
Finland+Hawaii+SD

39. Large statistics and good energy resolution needed!
Scintillator-like energy resolution, one detector in Finland

40. Can improve using relative timing information
Two scintillator
detectors
oscillation: red
timing: dark
One scintillator
detector + IceCube
(assume ~ 1 ms timing)
oscillation: red
timing: dark

41. Summary Current detectors: - ~Galactic sensitivity
(SK reaches barely to Andromeda)
- sensitive mainly to the ne component of
the SN flux
Near future
- more flavor sensitivity w/ HALO, Icarus
Next generation of detectors:
- extragalactic reach + DSNB
- richer flavor sensitivity
- very good neutrino-based pointing