Hermann Kolanoski Humboldt-Universitt zu Berlin and DESY Coll. - - PowerPoint PPT Presentation

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Hermann Kolanoski Humboldt-Universitt zu Berlin and DESY Coll. Ljubljana, 16. 3. 2015 H.Kolanoski - IceCube Neutrino Observatory 1 What I want to tell you: What want to you Cosmic rays (CR) Cosmic rays (CR) How to measure cosmic

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Hermann Kolanoski Humboldt-Universität zu Berlin and DESY

  • Coll. Ljubljana, 16. 3. 2015
H.Kolanoski - IceCube Neutrino Observatory 1
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What I want to tell you:

  • Coll. Ljubljana, 16. 3. 2015
H.Kolanoski - IceCube Neutrino Observatory 2

– Cosmic rays (CR) – How to measure cosmic rays – What we know and don‘t know about CR – Neutrinos as messengers of cosmic accelerators – Neutrino Observatory IceCube – The IceCube Muppet Show .... – Do not talk about e.g. exotic searches (wimps, …)

What want to you

Cosmic rays (CR) measure cosmic rays know and don‘t know about CR

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Cosmic Rays

  • Coll. Ljubljana, 16. 3. 2015
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100 years after their discovery not yet understood Kernfragmente

ion pairs / (cm3 s)

Cosmic

100 years after their discovery not yet understood Viktor Hess 1912 5 km height faster discharge

  • f an electrometer

with increasing height interpreted due to radiation from space: “Höhenstrahlung”

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Zwicky’s proposal for the CR Origin

  • Coll. Ljubljana, 16. 3. 2015
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“Cosmic rays are caused by exploding stars which burn with a fire equal to 100 million suns and then shrivel from ½ million mile diameters to little spheres 14 miles thick.”, says Fritz Zwicky, Swiss Physicist. In Los Angeles Times, Jan. 1934

… since then we are trying to prove it

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Cosmic Ray Spectrum

  • Coll. Ljubljana, 16. 3. 2015
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LHC(p) LHC(pp)

~ 32 decades ~ 32 decades ⇒ very different detection methods very different detector sizes ~E-2.7

cut-off?

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Cosmic Ray Spectrum

  • Coll. Ljubljana, 16. 3. 2015
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LHC(p) LHC(pp)

~ 32 decades ~ 32 decades ⇒ very different detection methods very different detector sizes ~E-2.7

cut-off?

Where and how are the highest energies produced??? What is the elemental composition? Galactic and/or extragalactic?

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  • Coll. Ljubljana, 16. 3. 2015
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Extensive Air Showers

Use the atmosphere as calorimeter

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Air Shower Detectors

  • Coll. Ljubljana, 16. 3. 2015
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IceTop IceTop

distance 125 m size 1 km2 energies PeV – EeV

1 km2 3000 km2

Pierre Auger Observatory

distance 1500 m size 3000 km2 energies EeV – 100 EeV

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PeV to EeV

  • Coll. Ljubljana, 16. 3. 2015
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3.14 2.90 3.37 𝛿=2.65 The fine structure in the spectrum M.G. Aartsen et al, Physical Review D88 (2013) 042004!

𝐺 = 𝐹−𝛿

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Confinement in the Galaxy

  • Coll. Ljubljana, 16. 3. 2015
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O Fe H

10 kpc

B e z p R : Rigidity ρ = = CR in galaxy: mean lifetime 107 years Energy has to be refueled. Where, how?

Emax ~ Z ⇒ Emax (Fe) ≈ 26 Emax (H)

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Origin and Physics of the knee(s)

  • Coll. Ljubljana, 16. 3. 2015
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If the knee is due to the diffusion out of the galaxy we expect a change in composition towards heavier elements spectrum below the knee: well known by direct measurements; above the knee: indirect measurements via air showers, difficult p knee Fe knee

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  • Coll. Ljubljana, 16. 3. 2015
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Cosmic Ray Anisotropy

The orientation of the dipole moment does not correspond to the relative motion (~200 km/s) in the Galaxy (Compton-Getting effect) Diffusive transport in galactic magnetic field from nearby sources?

IceCube

17 TeV 5 TeV

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Energy Dependence of CR Anisotropy

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Energy Dependence of CR Anisotropy Energy Dependence of CR Anisotropy

  • Coll. Ljubljana, 16. 3. 2015
H.Kolanoski - IceCube Neutrino Observatory
  • Anisotropy changes in position, size
  • Above 400 TeV there’s indication of

an increase in strength.

17 TeV 41 TeV 75 TeV 140 TeV 240 TeV 590 TeV 1.2 PeV 4.5 PeV

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Large and Small Scale Anisotropies

  • Coll. Ljubljana, 16. 3. 2015
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diffusive transport from nearby sources?

  • bserved small scale (10°) structures ⇒ few pc distance
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  • Coll. Ljubljana, 16. 3. 2015
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UHECR Results

cut-off at 1020 eV definitely observed

Cen A

28/84 = 33% isotropic background = 21% ➙ <1 % chance probability direction correlation with AGN?

Auger Observatory

GZK or source power limited?

(GZK = Greisen-Zatsepin-Kuzmin)

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  • Coll. Ljubljana, 16. 3. 2015
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CMB 2.7 K → threshold Ep ≈ 4×1019 eV “GZK horizon” ~160 Mly

Cosmic Rays, CMB Photons and Neutrinos

Cosmic Microwave Background (CMB): perfect blackbody at 2.74 K

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Nature of the Cutoff?

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Is this the “GZK cutoff”? Energy loss by collison with CMB photons? Or do accelerators run out of steam? ⇒ composition becomes heavier  Fe

  • Coll. Ljubljana, 16. 3. 2015
H.Kolanoski - IceCube Neutrino Observatory

Auger: Xmax with florescence detectors

data suggest change of composition from light to heavy Not GZK cutoff?

Clarification from other messengers? Are there GZK neutrinos?

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Where could particles possibly be accelerated? Hillas diagram

  • Coll. Ljubljana, 16. 3. 2015
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supernova remnants (SNR) gamma ray bursts (GRB) active galactic nuclei (AGN) black holes Emax ≈ 1018 eV z βs (L / kpc) (B / μG)

B L

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Cosmic Accelerators

  • Coll. Ljubljana, 16. 3. 2015
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Supernova Remnants (SNR)

Crab Nebula (explosion 1054)

Fermi acceleration at shock front 1 % of the energy of all SN explosions can explain energy density of cosmic rays in galaxy (~ 0.5 MeV/m3) However: No SNR has been clearly pinned down as source

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Charged Particle

Twisted and Straight Paths

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Absorption of γ‘s by γ γ -> e+e-

e+ e- γ γ

γγ

σ

s

e

m 2

s 1 ~

  • Coll. Ljubljana, 16. 3. 2015
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I know! I did γ γ → hadrons

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Cosmic Rays, Gammas and Neutrinos

  • Coll. Ljubljana, 16. 3. 2015
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target accelerator CR – ν connection the γ – ν connection for hadron accelerators ν spectrum ~ E-2 assumed

p

target ν ν ν

μ

±

π±

γ γ

π0

CR – γ connection

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Neutrino fluxes

  • Coll. Ljubljana, 16. 3. 2015
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Cosmic neutrinos should have a hard spectrum

F ~ E-2

atmospheric ν F ~ E-3.7

E-3.7 E-2

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How to detect cosmic high energy neutrinos?

  • Coll. Ljubljana, 16. 3. 2015
H.Kolanoski - IceCube Neutrino Observatory 24

quite difficult

⇒large target volume Most efficient: Cherenkov light from charged ν products ⇒ transparent ⇒water or ice

Lake Baikal Mediterranean Sea Absorption small  detection probability small

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Amundsen – Scott Station

  • Coll. Ljubljana, 16. 3. 2015
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Approaching the Pole these Days

  • Coll. Ljubljana, 16. 3. 2015
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Arriving at Pole

  • Coll. Ljubljana, 16. 3. 2015
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IceCube Neutrino Observatory

  • Coll. Ljubljana, 16. 3. 2015
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1000 m

  • 86 Strings, 2450 m deep
  • 5160 Optical Modules
  • Instrumented: 1 km3
  • IceTop: 1 km2
  • Installation: 2005-2011

IceCube DeepCore IceTop

air shower array neutrino telescope

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The Drill Camp

  • Coll. Ljubljana, 16. 3. 2015
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…. 2450 m deep

  • Coll. Ljubljana, 16. 3. 2015
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.. what you see down there

  • Coll. Ljubljana, 16. 3. 2015
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When the Season is over

  • Coll. Ljubljana, 16. 3. 2015
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The Last Flight at the End of the Season

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  • Coll. Ljubljana, 16. 3. 2015
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Detection of High Energy Neutrinos

  • Coll. Ljubljana, 16. 3. 2015
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extraterr. Neutrinos atmosph. Muons

Earth as filter

atmosph. Neutrinos

νµ

µ

km Energy

MeV GeV TeV PeV EeV ZeV Earth diameter

1012 102 104 106 108 1010

νµ +N→ µ + X

1 lightyear Radius Earth orbit

mean free path even for neutrinos the Earth becomes opaque above about 1 PeV ⇒ look upward – atm. background becomes less

density of Universe 10-23 × ρ(H2O)

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Detecting a Neutrino

  • Coll. Ljubljana, 16. 3. 2015
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Particle Signatures

  • Coll. Ljubljana, 16. 3. 2015
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  • muon tracks
  • em + had. shower

CR shower in IceTop µ bundle up-going νµ → point sources ν

µ

µ νe cascade → all flavours ν

e

µ background & physics W± l± νl N X CC Z0 νl νl N X NC

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Search for Diffuse Astrophysical Neutrino Flux Background: Atmospheric Neutrinos

  • Coll. Ljubljana, 16. 3. 2015
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~ 100,000 events per year “prompt” ν’s: from (semi-) leptonic decays of heavy hadrons (mainly charm). Flatter spectrum than “conventional” ν’s ⇒ large uncertainty for astro-ν’s IceCube has now constrained to ~ ERS model (Enberg et al.) E-2 astrophysical?

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  • Atmos. ν’s: background for one – Signal for the other

Neutrino Oscillation

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Detector

Atmospheric Neutrinos

Different direction = different pass length νμ disappearence Survival probability in the 2ν scheme Eν ≈ 10 – 100 GeV in DeepCore

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Neutrino Oscillation

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Disappearance atmospheric νμ with 3 years of data (for the normal hierarchy): sin2(θ23) = |∆m232| = ) =

arXiv:1410.7227 Ultimate goal: measure mass hierarchy with a densely instrumented extension: PINGU

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Search for Pointsources: The Method

  • Coll. Ljubljana, 16. 3. 2015
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Source background ≈ 2° - 3°

background: atmospheric ν Search for event excess within 2° - 3°

  • somewhere in the Northern sky
  • from list of candidate sources

4282 events (small sample)

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The Statistics Problem

  • Coll. Ljubljana, 16. 3. 2015
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If you search long enough you will for sure get an excess at some point “I only believe in statistics that I doctored myself”

Winston Churchill

Example: Expect 3 events background in a search window, but see 7. How significant is this?

0.05 0.1 0.15 0.2 0.25 1 2 3 4 5 6 7 8 9 10

w(n>6) = 3,3 % <n> = 3

Already for about 30 search windows the probability to see 7 or more events in any window is about 60% for background only. Significance is determined by ~10000-fold simulation of measurement

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Hottest spot in South: p-value* ≈ 10-6 (pre-trial) Ra: 296.95 Dec: -75.75 Ns=16.16 γ =2.34 p-value* ~ 9.3% (post-trial)

*p-value for background only
  • Coll. Ljubljana, 16. 3. 2015
H.Kolanoski - IceCube Neutrino Observatory

Point Source Search 2008-2011

IC86+79+59+49

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Improving Statistical Significance

  • Coll. Ljubljana, 16. 3. 2015
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  • pre-defined source positions
  • pre-defined time-window
  • „stacking“ of pre-defined sources

„Pre-Definition“ with „multi-messenger“ information of

  • ptical, gamma, X-ray, radio telescopes …
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  • Coll. Ljubljana, 16. 3. 2015
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  • Intense flashes of gamma rays
  • Duration some seconds
  • highly-relativistic jet (‘fireball’)

Search for neutrinos which are in time and direction consistent with GRB

GCN: The Gamma-ray Coordinates Network

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Are GRBs the main sources of Cosmic Rays?

  • Coll. Ljubljana, 16. 3. 2015
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225 GRB ... no coincidences observed Standard Fireball Models excluded [Nature 484 (2012) 351]

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Extremly High Energy (EHE) Neutrinos

  • Coll. Ljubljana, 16. 3. 2015
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threshold ~ 5 × 1019 eV

GZK

Search for high number of Cherenkov photons = NPE θ = zenith angle Search region up-going down-going upward downward

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Search for cosmogenic neutrinos with 2010-2012 data.

  • Two shower type events found in 616 days of IceCube observations.
  • Neutrino energies could be higher than deposited energies, if neutral

current interaction.

  • Coll. Ljubljana, 16. 3. 2015
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  • Aug. 8, 2011

1.04 ± 0.14 PeV

  • Jan. 3, 2012

1.14 ± 0.14 PeV

deposited energies

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The Muppet Show

  • Coll. Ljubljana, 16. 3. 2015
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A detection of 1 neutrino is interesting … 2 is evidence … … and 3 is a spectrum!

A theoreticians view (Francis Halzen, IceCube PI) :

1.04 ± 0.14 PeV 1.14 ± 0.14 PeV 2.00 ± 0.26 PeV

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.

Follow-up Search

for contained and semi-contained events

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  • find contained events below the energy threshold
  • f the “Bert-and-Ernie” analysis

– same dataset, 662 days of livetime

  • Use outer IceCube layers as incoming track veto

– Additional atmospheric muon veto – Sensitive to all flavors in region above ~ 60TeV – Muon background can be estimated from data

μ Veto μ νμ

✓ ✘

Effective volume

  • Coll. Ljubljana, 16. 3. 2015
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Some example events

  • Coll. Ljubljana, 16. 3. 2015
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declination: -0.4° deposited energy: 71TeV declination: -13.2° deposited energy: 82TeV declination: 40.3° deposited energy: 253TeV

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Excess of HE Starting Tracks

  • Coll. Ljubljana, 16. 3. 2015
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Significance about 5.7 σ

First observation of astrophysical flux of high energy neutrinos

Starting events depositing >60 TeV using 3 years of data, events up to ~2 PeV

  • Phys. Rev. Lett. 113, 101101
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Global Fit to 6 Different Measurements

  • Coll. Ljubljana, 16. 3. 2015
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Simplest model: flux and flavor ratio

Results:

Flavor ratio compatible with

„prompt“ < 2 × ERS

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Skymap

  • Coll. Ljubljana, 16. 3. 2015
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equatorial coordinates

no significant correlation with galactic plane

p-value: 7%

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Blazars or GRB as Sources?

  • Coll. Ljubljana, 16. 3. 2015
H.Kolanoski - IceCube Neutrino Observatory 57

Compare directions of the high energy νμ with directions of Blazars observed by Fermi Satellite at high γ luminosity Even more stringent for GRB: from analysis of 506 GRBs in four years it was found that no more than 1% of the high energy neutrinos could come from GRB 1% atmost from GRBs high luminosity 17% atmost from Blazars

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  • Coll. Ljubljana, 16. 3. 2015
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Anything new down there?

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CONCLUSION

  • Coll. Ljubljana, 16. 3. 2015
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„Alles Wissen und alle Vermehrung unseres Wissens endet nicht mit einem Schlußpunkt, sondern mit Fragezeichen“

Hermann Hesse .

?

… imagine Sisyphos to be happy

»… il faut imaginer Sisyphe heureux« A.Camus

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