Astronomy and physics with cosmic neutrinos
Transcript of Astronomy and physics with cosmic neutrinos
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Uli Katz, Erlangen Centre for Astroparticle Physics
Physics Colloquium, TU Chemnitz
13 January 2016
Astronomy and physics with cosmic neutrinos
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The plan for the next hour
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 2
• Introduction to neutrino astronomy
• First detection of cosmic neutrinos with IceCube
• Neutrino astronomy in the Mediterranean Sea
• Particle physics with neutrino telescopes
• Summary and outlook
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Neutrino astronomy
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
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The mysterious cosmic rays
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
LHC
~E-2.7
~E-2.7~E-3
ankle 1 part km-2
yr-1
knee 1 part m-2 yr-1
• Particles impinging on Earth from outer space carry energies up to
1021 eV(the kinetic energy of a tennis ball at ~200km/h.)
• The acceleration mechanisms are unknown.
• Cosmic rays carry a significant fraction of the energy of the universe –cosmologically relevant!
• Neutrinos play a key role in studying the origin of cosmic rays.
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Neutrino production mechanism
• Neutrinos are produced in the interaction of high energy nucleons with matter or radiation:
YYKXN )(...)(
)()(
eee
0 N X Y Y
• Simultaneously, gamma production takes place:
Cosmic rays
• Cosmic ray acceleration yields neutrinos and gammas!
• … but gammas also from purely leptonic processes
Cosmic rays
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 5
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Particle propagation in the Universe
Photons: absorbed on dust and radiation;
Protons/nuclei: deviated by magnetic fields, reactions with radiation (CMB)
1 parsec (pc) = 3.26 light years (ly)
gammas (0.01 - 10 Mpc)
protons E>1019 eV (few 10 Mpc)
protons E<1019 eV
neutrinos
Cosmic accelerator
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 6
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How does a neutrino telescope work?
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Neutrino interacts in the
(vicinity of the) telescope
• Charged secondaries cross
the detector volume (water or
ice) and stimulate Cherenkov
emission
• Recorded by a 3D-array of
photo-sensors
• “Traditional” channel:
• Energy range :
10(0) GeV – some PeV
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Backgrounds, or maybe not
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Atmospheric neutrinos from cosmic-ray interactions in atmosphere
• irreducible
• important calibration source
• allow for oscillation studies
• Atmospheric muons from cosmic-ray interactions in atmosphere above NT
• penetrate to NT
• exceed neutrino event rate by several orders of magnitude
• Sea water: light from K40 decays and bioluminescence
p
Atmosphere
Earth
p
NT
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The telescope world map
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
Lake Baikal
onde
(custom-built sensor groups)DUMAND
IceCube (South Pole)
KM3NeT: A distributed multi-km3 neutrino
telescope in the Mediterranean Sea
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Example targets of astronomy
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Galactic neutrino sources
Example: Supernova remnant RX J1713
Gamma observation by H.E.S.S.
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Example targets of astronomy
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Galactic neutrino sources
• Extragalactic sources
Active Galactic Nuclei (AGN):
Super-massive black hole in centre of galaxy
with accretion disk and jet emission
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Example targets of astronomy
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Galactic neutrino sources
• Extragalactic sources
• Transient sources
Extremely bright gamma ray flash (sec-min)
from hypernovae or BH/NS mergers or …
Isotropic distribution extragalactic
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Example targets of astronomy
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Galactic neutrino sources
• Extragalactic sources
• Transient sources
• Diffuse neutrino flux
Isotropic high-energy neutrino flux
above atmospheric neutrino background
from unresolved astrophysical sources
or of cosmogenic origin (GZK)
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Example targets of astronomy
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Galactic neutrino sources
• Extragalactic sources
• Transient sources
• Diffuse neutrino flux
• Neutrinos from Dark Matterannihilations
• Particle physics with atmospheric neutrinos
• Search for exotics(monopoles, nuclearites,…)
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South Pole and Mediterranean Fields of View
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
> 75%> 25%
Galactic coordinates
2 downward sensitivity assumed
IceCube @South Pole:Sees Northern hemisphere
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South Pole and Mediterranean Fields of View
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
> 75%> 25%
Galactic coordinates
2 downward sensitivity assumed
IceCube @South Pole:Sees Northern hemisphere
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IceCube and the first
detection of cosmic neutrinos
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
Several slides adapted from:
F. Halzen: “IceCube: the discovery of cosmic neutrinos”, VHEPA 2016
K. Hanson: “IceCube Gen2”, VHEPA 2016
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IceCube: A km3 detector in the Antarctic ice
18U. Katz: Neutrino Astronomy, 04.03.2013Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 18
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The IceCube detector
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• 86 strings altogether
• 125 m horizontal spacing
• 17 m vertical distance between Optical Modules
• 1 km3 instrumented volume, depth 2450m
• Deep Core
• densely instrumented region in clearest ice
• Completed in Dec. 2010
• Extremely stable and efficient operation since then
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A first glimpse at cosmic ’s
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
● First PeV events found in 2011/12 (deposited energy > 1015 eV)
● Hardly consistent with atmospheric neutrino background
● Note: Cascade events without muon tracks
Aug. 9, 2011
Bert
Jan 3, 2012
Ernie
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A first glimpse at cosmic ’s
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
● First PeV events found in 2011/12 (deposited energy > 1015 eV)
● Hardly consistent with atmospheric neutrino background
● Note: Cascade events without muon tracks
Aug. 9, 2011
Bert
Jan 3, 2012
Ernie
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Big Bird, 2.0 PeV
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Systematic search for such events …
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Select events interacting
inside the detector only
• No light in the veto region
• Veto for atmospheric
muons and neutrinos
(which are typically
accompanied by muons)
• Energy measurement:
total absorption calorimetry
• “High-energy starting
events” (HESE)
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… success!
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
104
105
106
0
10
100
250
100
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106
Eve
nts
pe
r 6
62
da
ys
Data (Trigger Level)Signal Region
Total Charge (PE)
Vet
o R
egio
n C
harg
e (P
E)
Eve
nts
pe
r 6
62
da
ys
26 events in
one year
of data!
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After 4 years:
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
7s excess of neutrinos
of all flavours over
background expectations
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After 4 years:
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
7s excess of neutrinos
of all flavours over
background expectations
6s excess of
muon neutrinos over
background expectations
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Where do they come from?
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
2 years HESE
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Where do they come from?
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
3 years HESE
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Where do they come from?
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
4 years HESE
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Correlation with Galactic plane?
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
Test statistic
2.5% if 7.5°width of Galactic
plane assumed
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Neutrino flavor composition?
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
µ
et
• Neutrinos from
p/K decays
oscillate to
e:µ:t = 1:1:1
over cosmic
distances
• IceCube
measures
mostly µ:(e+t)
• Result
consistent
with expectation
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Questions, no answers (yet)
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• A non-power-law component? Different source classes?
• Attention: Neutrinos are absorbed in Earth above ~100 TeV 31
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IceCube events from blazars?
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Multi-messenger analysis
using Fermi-LAT and radio
data
• Candidate source for Big
Bird: “Flat-spectrum radio
quasar (FSRQ)” B1424-418
– temporally and spatially
coincident
• Consistent with
astrophysical modelling
• Probability for random
association 5%
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The IceCube signal
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Confirmed with high significance in cascade and muon channels
• Consistent with being fully isotropic
• Flavour composition consistent with /K decay origin
• Possible structure in energy spectrum around 100 TeV?
• Origin is still unclear!
More data needed to draw firm conclusions!
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Future plans: IceCube Gen2
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• PINGU:
low energy, mass hierarchy
• High Energy Array (HEA): PeV
scale neutrinos
• Cosmic Ray Array (CRA): veto
array for HEA,
cosmic ray physics
• Radio Array (RA):
array of RF power envelope
detectors
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Neutrino astronomy in
the Mediterranean Sea:
ANTARES and KM3NeT
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
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ANTARES: The first deep-sea telescope
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 36
• Installed near Toulon at a depth of 2475m
• 12 strings with 25 storeys each, instrumented volume ~0.01km3
• Data taking in full configuration since 2008
• Proof of principle of deep-sea telescope
• Lots of results – but (too) small for cosmic neutrinos
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ANTARES and IceCube: Combined analysis
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 37
• Common analysis of ANTARES and IceCube data
• Search for point-like neutrino sources, spectrum ~ E – * cutoff(Ecutoff)
• Substantial contribution from ANTARES for spectra with Ecutoff ~ 100 TeV
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The KM3NeT concept
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 38
● Deep-sea array of
photodetectors
● Multi-PMT modules
(31 3’’-PMTs in one sphere)
● 18 modules per string
(detection unit)
● 115 strings per building block
● All data to shore
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Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
The KM3NeT Collaboration
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A
B
CC
D
PMT
The KM3NeT Digital Optical Module
• 31 3-inch PMTs in 17-inch glass sphere (cathode area~ 3x10-inch PMTs)
• 19 in lower, 12 in upper hemisphere
• Suspended by plastic structure
• 31 PMT bases (total ~140 mW) (D)
• Front-end electronics (B,C)
• Al cooling shield and stem (A)
• Single penetrator
• Advantages:
• Increased photocathode area
• 1-vs-2 photo-electron separation better sensitivity to coincidences
• Directionality
• Cost / photocathode area
• Minimal number of penetrations reduced risk
40Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
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The KM3NeT detection unit (DU)
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 41
• Mooring line:
• Buoy (syntactic foam or empty spheres)
• 2 pre-stretched Dyneema© ropes (4 mm diameter)
• 18 storeys (one DOM each)
• Electro-optical backbone (VEOC):
• Flexible hose ~ 6mm diameter
• Oil-filled
• Optical fibres and copper wires
• At each storey: Break-out box for connection to 1 fibre + 2 wires (one single pressure transition)
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Deployment
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 42
• Deploy
to sea bed
• Acoustic
release
• Unfurl
• Collect
frame
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The building block concept
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 43
• Building block:
• 115 detection units
• Segmentation enforced by technical reasons
• Large block (neutrino astronomy)
• Sensitivity per string for muons independent of block size above ~75 strings
• One block ~ half IceCube
• Small block (neutrino oscillations)
• Precision measurement of atmospheric neutrinos
• One block ~ 6 Mtons
• Allows for staged, block-wise, multi-site installation
DU distance adjusted to scientific objective:90-120 m for neutrino astronomy /
20 m for oscillation research
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KM3NeT development
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 44
Phase Blocks/
strings
Primary deliverables /
site(s)
Funding
Construction
1 0.2/31Proof of feasibility and first science results;KM3NeT-Fr + KM3NeT-It sites
Fully funded
2015-17
2.0
2/230Measurement of neutrino signal reported by IceCube;All-flavor neutrino astronomy;KM3NeT-It site
Applications
pending
2017-2020
1/115Neutrino mass hierarchy;KM3NeT-Fr site
3 6+1/805Neutrino astronomy including Galactic sources;Multiple sites
t.b.d.
?
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KM3NeT Phase-1 = 31 DUs
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 45
ARCA =
Vertical OM distance = 36 m
3 times ANTARES
ORCA =
Vertical OM distance = 9 m
Astroparticle
Research with
Cosmics in the
Abyss
Oscillation
Research with
Cosmics in the
Abyss
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KM3NeT 2.0 = ARCA and ORCA
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 46
ARCA =Vertical OM distance = 36 m
ORCA =
Vertical OM distance = 9 m
Astroparticle
Research with
Cosmics in the
Abyss
Oscillation
Research with
Cosmics in the
Abyss
+
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DOM prototype (PPM-DOM)
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 47
K40 coincidence rate
PMT efficiencies
Up to 150
Cherenkov
photons
per decay
e- (β decay)
40K40Ca
Concentration of 40K is stable
(coincidence rate ~5 Hz on adjacent PMTs)
Coincidence rate on 2 adjacent PMTs
(33°angular separation)
Peak position
time offsets
Eur.Phys.J. C74 (2014) 3056
Deployed at
ANTARES in
April 2013
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PPM-DOM: Atmospheric muons
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 48
Number of coincident hits in a DOM Zenith angle of hit PMTs in events
with more than 7 coincident hits
>5 coincidences within 20ns ºreduced K40 contribution,
dominated by atmospheric muons
More upper PMTs in multi-hit events ºdirectional information
from single storey
Eur.Phys.J. C74 (2014) 3056
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PPM-DU: Muon reconstruction
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 50
• Reconstruct
muon trajectory
from hits on
3 DOMs
• Ambiguities can
be reduced by cuts
on time differences
• 7°FWHM resolution
achieved
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First string deployed on 3 Dec 2015
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 51
• Smooth operation
• All 18 DOMs alive and
functional
• First muons reconstructed
within hours after switch-on
• Data taking in progress
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Muon angular reconstruction
Reconstruction using new PMT response simulation:
Median of angle DW between reconstructed µ and true ν direction
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
Expected
µ reconstruction
precision
0.1°
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Shower reconstruction: Method
● Vertex fit: Suitable hit selection, fit uses timing;
result used for containment requirement
● Direction and energy: Uses PDF depending on
● Distance vertex – DOM
● Angle between shower direction and DOM
● Orientation of PMTs
● Hit information used: yes/no
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Shower reconstruction: θ, E
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
● For contained νe CC events
● Event sample after selection cuts
● ~10% in E, better than 2°in direction
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Assumptions:
1. Flavour-symmetric
2. Isotropic
3. Energy spectrum
consistent with IceCube
findings
Diffuse extragalactic neutrino flux
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.201655
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Diffuse flux results (max. liklihood)
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz,
13.01.2016
Muon
analysis
Other flux assumptions
yield 10-30% improvement
in discovery time.
Event numbers
(cut&count):
16/9 cascades
7.5/5 track-like
(signal/background
per ARCA year)
Note:
For each energy,
direction and flavour,
KM3NeT is
complementary to
IceCube
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Point-source results
● Galactic sources in reach
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Significant discovery
potential for extragalactic
sources
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Point-source search with cascades
● Results are
“rather
preliminary”
● Important:
Provides
cascade event
sample for
source
candidates
● Closes
visibility gap
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Particle physics with
neutrino telescopes
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
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Oscillations of atmospheric neutrinos
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Neutrino telescopes observe large numbers of atmospheric neutrinos
• Path length through Earth depends on zenith angle (0–12.000 km)
• Can we use them to study neutrino physics? … Yes!
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Neutrino oscillations in vacuum
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Neutrino flavour and mass eigenstates are not the same:
• Consequence: Neutrino oscillationsVery simplified case: 2 flavours, vacuum
• No information on sign of
• In the above units:
no effectobserve oscillationsobserve averaged oscillations
(propagation) (production)
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• Parameterisation of mixing matrix (up to Majorana phases that are not discussed here):
• Neutrino oscillation parameters (only central values given):
atmos. + acc.solar + reactor
reactor (2012)
• Unknown: sign of
CP-violating phase
The 3-flavour case
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The neutrino mass hierarchy
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Depending on sign of :
“normal hierarchy” or “inverted hierarchy”
(NH) (IH)
• A fundamental parameter of particle physics! Knowledge required to investigate neutrino CP violation
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• Neutrino propagation in matter different for and :
W and Z exchange
Z exchange only
Result: Modification of oscillation pattern
• Dominant cause of solar neutrino oscillations (MSW effect)
• For atmospheric and :
Matter effect depends on sign of
Same effect for and
• Atmospheric neutrinos offer just the right
and to measure the effect.
• In neutrino telescope: and cannot be distinguished,
but net effect since
Neutrino oscillations in matter
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Oscillations of atmospheric neutrinos
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Determining the sign of requires matter effect.Oscillation of must be involved.
• 3-flavour oscillations of in matter:
• “Matter resonance” for(maximal mixing, minimal oscillation frequency).This is the case for
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Neutrino oscillations in the Earth
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Earth density 4-13 g/cm3
• Relevant:
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Mass hierarchy “oscillogram”
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 67
Akhmedov, Razzaque, Smirnov:
JHEP 1302 (2013) 082, JHEP 1307 (2013) 026
• Expected signal significance in energy vs. zenithw/o experimental effects
• Need to assessneutrino reactionsat 3–20 GeV
• Required:
• Good angular and energy resolution
• Flavour separation
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… and in the real world
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 68
• Both muon (µ survival) and electron channel (µe conversion) contribute
• Removal of atmospheric muon background essential
• Major effort to control systematics
• But: Measurement in reach
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Measuring the mass hierarchy
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016 69
• Sensitivity depends ontrue value ofθ23 (“the octant”)
• 3σ in 3 yearsfor most unfavourable situation
• Similar resultfor PINGU, butlater starting date
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… concluding
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
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Summary and outlook
Astronomy and physics with cosmic neutrinos (U.Katz) Physics Colloquium, TU Chemnitz, 13.01.2016
• Neutrino astronomy has become mature –
transition from searches to observation
• Addressing fundamental questions of particle and
astrophysics, and of cosmology
• Cubic-kilometre detectors required
• Full sky coverage by IceCube and KM3NeT,
complementary environments and sensitivities
• Addressing central questions of neutrino physics
Stay tuned!
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