OUTLINE
Neutrinos from supernovaeSupernova neutrino detection Inverse beta decay Other CC interactions NC interactionsSummary of current and near future detectorsFarther future detectors Extra galactic neutrinos Relic neutrinos Pointing to a supernova with neutrinosSummary
What do we want in a SN 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 Flavor sensitivity
Sensitivity to different flavors and ability to tag interactions is key!
e vs
e vs
x
Require NC sensitivity for , since SN
energies below CC threshold
Good old CC inverse beta decay , the workhorse of neutrino physics, serves us well for SN neutrino detection:
Inverse Beta Decay (CC)
e + p e+ + n
In any detector with lots of free protons (e.g. water, scint) this dominates by orders of magnitude
Can often exploit delayed (~180 s) coincidence of n + p d (or other neutron capture) as tag (also possibly 's from e+ annihilation)
e+
n
2.2 MeV
0.511 MeV
0.511 MeV
e
WATER CHERENKOV DETECTORS
Volume of clear water viewed by PMTs
- few 100 events/kton
Super-Kamiokande IV 22.5 kton f.v.: ~8000 inverse betadecay events @ 10 kpc
- typical energy threshold ~ several MeV makes 2.2 MeV neutron tag difficult
Possible enhancement:
Beacom & Vagins, hep-ph/0309300
Gd has a huge n capture cross-section: 49,000 barns, vs 0.3 b for free protons;
R&D is currently underway for SK with half kton test tank in the Kamioka mine
use gadolinium to capture neutrons for tag of e
n + Gd Gd* Gd +
e + p e+ + n
€
Eγ∑ = 8MeV
Previously used in small scintillator detectors;may be possible for large water detectors with Gd compounds in solution
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
e's as coincident
increase in single PMT count rates (M
eff~ 0.4 kton/PMT)
IceCube at the South Pole
cannot tag flavor, or other interaction info, but gives overall rate and time structure
SCINTILLATION DETECTORS
Liquid scintillator CnH
2n
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)
+Double Chooz, Daya Bay and RENO
(+Cherenkov)
NOA: long baseline oscillation experiment (Ash River, MN)
15 kton scintillator, near surfaceK. Arms, CIPANP ‘09
CC interactions on nuclei play a role, too
e + (N,Z) (N-1, Z+1) + e-
e + (N, Z) (N+1, Z-1) + e+
Nuclear physics important in understanding cross-sections and observables! ... often large uncertainties, need to measure!
e + n p + e- :
e + p n + e+ :
Observables for tagging
- charged lepton e+/- - possibly ejected nucleons- possibly de-excitation 's
For most existing (and planned) large detectors, inverse beta decay dominates, (and is potentially taggable) so primary sensitivity is to
e
dependson nucleus
(cross-sections smaller for bound nucleons)
Examples of CC interactions of SN with nuclei:
Interactions with oxygen in water
e + 16,18O 16,18F + e-
e + 16O 16N + e+
e.g. Super-K,~few tens @ 8.5 kpc
Interactions with carbon in scintillator
e + 12C 12N + e-
e + 12C 12B+ e+
e.g. LVD, KamLAND, Borexino~few @ 8.5 kpc
e + 40Ar e- + 40K*
- Tag modes with gamma spectrum (or lack thereof)- Excellent electron neutrino sensitivity
e,x
+ e- e,x
+ e-
x + 40Ar
x + 40Ar*
CC
NC
ES
Ethr
=1.5 MeV
Ethr
=7.48 MeV
Ethr
=1.46 MeV
ICARUS: 600 ton LAr
e + 40Ar e- + 40Cl*
_
Relative rates depend on energy spectral sensitivity (oscillation sensitivity)
e + 208Pb 208Bi* + e-
1n, 2n emission
CC, Ethr=18 MeV
x + 208Pb 208Pb* +
x
1n, 2n, emission
NC
HALO at SNOLab
SNO 3He counters + 76 tons of Pb: ~85 events @ 10 kpc
fromT. Massicotte thesis
Also: elastic scattering (CC and NC contributions)
POINTING from Cherenkov cone: (degraded by isotropic bg)
e,x
+ e- e,x
+ e-
Super-K: expect few hundred ES for 10 kpc SN ~ 8o pointing
In water Cherenkov and scintillator, few % of inverse dk rate
e,x e-
(probably best bet for pointing)
Beacom & Vogel, astro-ph/9811359Tomas et al., hep-ph/0307050
€
Δθ ≈250
N
We have sensitivity to electron flavor neutrinos via CC interactions... but ~2/3 of the luminosity is andflavor; can be detected via NC interactions only
Again, nuclear physics matters!
Typically, signature is nucleon emission or nuclear de-excitation products
x + (A,Z) (A,Z)* +
x
e.g. x + (A,Z) (A-1,Z) + n +
x
(A,Z) +
sometimesgood tagis possible
Examples of NC interactions
Interactions with oxygen in water
e.g. Super-K, ~few hundreds @ 8.5 kpc
Interactions with carbon in scintillatore.g. LVD, KamLAND,Borexino~few tens @ 8.5 kpc
x + 12 C
x +
12C*
12C +
x + 16O
x +
16O*
16O + 's
15.11 MeV
K. Langanke et al., nucl-th/9511032
J. Beacom et al., hep-ph/0205220
NC neutrino-proton elastic scattering
x + p
x + p
Recoil spectrum in KamLAND
Recoil energy small, but visible in scintillator (accounting for 'quenching' )
Expect ~few 100events/kton for 8.5 kpc SN
Neutrino-nucleus NC elastic scattering in ultra-low energy detectors
High x-scn but very low recoil energy (10's of keV)
e.g. Ar, Ne, Xe, Ge, ...
x energy information
from recoil spectrum
possibly observable in solar pp/DM detectors
~ few events per ton for Galactic SN
C. Horowitz et al., astro-ph/0302071x + A
x + A
DM detectors, e.g. CLEAN/DEAP
Spherical Xe TPCAune et al.
Summary of SN neutrino detection channels
Inverse beta decay: - dominates for detectors with lots of free p (water, scint)
- e sensitivity; good E resolution; well known x-scn;
some tagging, poor pointing
CC interactions with nuclei: - lower rates, but still useful,
e tagging useful (e.g. LAr)
- cross-sections not always well known
Elastic scattering: few % of invdk, but point!
NC interactions with nuclei: - very important for physics, probes and flux - some rate in existing detectors, new observatories - some tagging; poor E resolution; x-scns not well known - coherent -p, -A scattering in low thresh detectors
e + p e+ + n
Current supernova neutrino detectorsDetector Type Location Mass
(kton)Events @ 8 kpc
Status
Super-K Water Japan 32 8000 Running (SK IV)
LVD Scintillator Italy 1 300 Running
KamLAND Scintillator Japan 1 300 Running
Borexino Scintillator Italy 0.3 100 Running
IceCube Long string South Pole 0.4/PMT N/A Running
Baksan Scintillator Russia 0.33 50 Running
Mini-BOONE
Scintillator USA 0.7 200 Running
e + p e+ + n
Primary sensitivity is to electron antineutrinos via inverse beta decay
Current and near-future supernova neutrino detectors
Detector Type Location Mass(kton)
Events @ 8 kpc
Status
Super-K Water Japan 32 8000 Running (SK IV)
LVD Scintillator Italy 1 300 Running
KamLAND Scintillator Japan 1 300 Running
Borexino Scintillator Italy 0.3 100 Running
IceCube Long string South Pole 0.4/PMT N/A Running
Baksan Scintillator Russia 0.33 50 Running
Mini-BOONE
Scintillator USA 0.7 200 Running
HALO Lead Canada 0.076 85 Under construction
Icarus Liquid argon Italy 0.6 230 Almost ready
NOA Scintillator USA 15 3000 Construction started
SNO+ Scintillator Canada 1 300 Funded
Plus: reactor scint detectors, coherent A scattering detectors, geochemical
Current best neutrino detectors sensitive out to ~ few 100 kpc.. mostly just the Milky Way
31 per century
SK
Mton
doubles
singles{
Looking beyond: number of sources α D3
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 's or grav wave/optical coincidence
S. Ando et al., astro-ph/0503321
Next generation mega-detectors (10-20 years)
Megaton-scale water detector concepts
Memphys
10-100 kton-scale scintillator detector concepts
5-100 kton-scale LAr detector concepts
LENA, HanoHano
Hyper-K
DUSELLBNE
8B flux
hep flux
atm. e
flux
SRN window!
M. Goodman
And going even farther out: we are awash in asea of 'relic' or diffuse SN 's (DSNB), from ancient SNae
Learn about star formation rate, which can constrain cosmological models
Difficulty is tagging for decent signal/bg(no burst, 2 coincidences optical SNae...)
C. Lunardini
M. Nakahata, Neutrino 2008 talke + p e+ + nIn water:
- 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)
~0.1 event/kt/year
low rate of return, but a sure thing
~300 events/kt/30 year
(Of course if you build a big detector and run it a long time, you may get both! Diversify!)
DSNB Galactic SN
more background less background
risky in the short term, but youwin in the very long term
~10 events/kt/yr
bonds vs stocks...
(But we must remember that no experiment is ‘too big to fail’... )
Summary of supernova neutrino detectorsG
alac
tic
sen
siti
vity
Ext
rag
alac
tic
Detector Type Location Mass(kton)
Events @ 8 kpc
Status
Super-K Water Japan 32 8000 Running (SK IV)
LVD Scintillator Italy 1 300 Running
KamLAND Scintillator Japan 1 300 Running
Borexino Scintillator Italy 0.3 100 Running
IceCube Long string South Pole 0.4/PMT N/A Running
Baksan Scintillator Russia 0.33 50 Running
Mini-BOONE
Scintillator USA 0.7 200 Running
HALO Lead Canada 0.076 85 Under construction
Icarus Liquid argon Italy 0.6 230 Almost ready
NOA Scintillator USA 15 3000 Construction started
SNO+ Scintillator Canada 1 300 Funded
LBNE LAr Liquid argon USA 5 1900 Proposed
LBNE WC Water USA 300 78,000 Proposed
MEMPHYS Water Europe 440 120,000 Proposed
Hyper-K Water Japan 500 130,000 Proposed
LENA Scintillator Europe 50 15,000 Proposed
GLACIER Liquid argon Europe 100 38,000 Proposed
Elastic scattering off electrons is the best bet
e,x
+ e- e,x
+ e- In water Cherenkov few % of total rate
~25o
N
e,x e-
POINTING to the supernova with future detectors (should be prompt if possible)
G. Raffelt
LBNE WC / Hyper-K / MEMPHYS: <~ 1o pointing
Other possibilities: - time triangulation - inv. dk e+n separation - ~TeV neutrinos (delayed)
Tomas et al. hep-ph/0307050
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)
For a known pathlength, the supernova will be found on a ring on the sky
KS, A. Burgmeier, R. WendellarXiv: 0910.3174
Inverse energy spectrum, L=6000 km
Power spectrafor different L
Peak in powerspectrum vs L for 500,000simulated SNae,60,000 events each (perfect energy resolution) measure kpeak to find
allowed L values
A. S. Dighe, et al. hep-ph/ 0311172
One detectorPerfect energy resolution60,000 neutrino eventsSN at dec=-60o, RA=20h, 0:00Finland
Two detectorsFinland+Hawaii
Three detectorsFinland+Hawaii+SD
Example skymaps
Large statistics and good energy resolution needed!
Scintillator-like energy resolution, one detector in Finland
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
SummaryCurrent detectors: - ~Galactic sensitivity (SK reaches barely to Andromeda)
- sensitive mainly to the e 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