alexander kappes forschungsseminar institut für physik, humboldt-universität berlin, 11. february...

Alexander KappesForschungsseminarInstitut für Physik, Humboldt-UniversitätBerlin, 11. February 2011

Fishing for Neutrinosin the Mediterranean Sea –ANTARES and KM3NeT

Alexander Kappes, Forschungsseminar, Humboldt-Universität, 11.02.2011 2cc

Outline

Introduction to neutrino astronomy

The ANTARES neutrino telescope

Selected results from ANTARES

The future Mediterranean neutrino telescope KM3NeT


1912: Discovery of Cosmic Rays (Victor Hess)• Observations before 1912:

- Elektroscopes dischargedue to natural radioactivity

• Balloon experiments since 1912: (Hess, Kolhörster)

- Discharge increases above ~1.5 km altitude

- Conclusion: Ionising radiation from outer space

Measurements Victor Hess (1912)


Cosmic rays:

• spectrum measured over12 orders of magnitudein energy

• power law spectrum(non thermal)

• consists of particles

Sources still unknown !

. . . 99 Years LaterCosmic ray spectrum

109 1012 1015 1018 1021

energy (eV)

10-27

10-21

10-15

10-9

10-3

103

Flu

x (G

eV-1 m

-2 s

-1 s

r-1)

LHC


The High-Energy Universe

gamma-ray bursts(GRB 080319B, X-ray, SWIFT)

active galactic nuclei(artist’s view)

supernova remnants(SN1006, optical, radio, X-ray)

micro-quasars(artist’s view)


Accelerator (source)

• Shock fronts (Fermi acceleration)

• Objects with strong magnetic fields (pulsars, magnetars)

Beam dump (secondary particle production)

• Interaction with photon and matter near the source

• Protons: pion decay

• Electrons: inverse Compton-scattering of photons

e + γ → e + γ (TeV)

High-Energy Particle Production in the Universe

p + p(γ) → π± + X μ + νμ

e + νμ + νe

p + p(γ) → π0 + X γ + γ (TeV)


Why Neutrino Astronomy?

• Neutrinos are produced in cosmological objects

• Neutrinos point back to the source

• Neutrinos travel cosmological distances

• Neutrinos escape from optically thick sources

• Neutrinos are a clear sign for hadron acceleration

Neutrinos provide complementary information to gamma-rays and protons


Principle of Neutrino Detection

muon

νμnuclearreaction

cascade43°

νμ

μTime & position of hits

μ (~ ν) trajectory Energy

PMT amplitudes


• Flux from above dominated by atmospheric muons

• Neutrino telescopes mainly sensitive to neutrinos from below

Background: Atmospheric Muons and Neutrinos

atmosphere

cosmicrays

μνμ

νμ

signal

background

p

p

μνμ

Alexander Kappes, Forschungsseminar, Humboldt-Universität, 11.02.2011 10

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Neutrino Telescope Projects

IceCubeIceCube

BaikalBaikalBaikalBaikalANTARESANTARESANTARESANTARES

NESTORNESTORNESTORNESTORNEMONEMONEMONEMO


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Sky Coverage

Visibility ANTARES (Mediterranean) > 75% 25% – 75% < 25%

TeV γ-ray sources Galactic extra-Galactic

Visibility IceCube (South Pole) 100% 0%


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The ANTARES

Neutrino Telescope


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ANTARES in the Mediterranean

Submarine cable (45km)

Shore Station


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The ANTARES Neutrino Telescope

-1995 m

-2475 m

• 12 lines (885 PMTs)+1 instrumentation line

• Instrumented volume: ~0.01 km3

2 m


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ANTARES Storey

Hydrophone:acoustic positioning

Optical Module:10” Hamamatsu PMTin 17” glass sphere photon detection

Local Control Module(in Ti cylinder):Front-endClock, tilt/compass, power distribution…

Titanium frame: support structure

Optical Beaconwith blue LEDs:timing calibration


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Construction

Milestones

• 2001 Installation of 40 km electro-optical cable

• 2002 Deployment and connection

of junction box

• 2003–2005 Installation ofprototype lines

• 2006–2008 Installation of 12 lines

• Detector completed since May 2008

Line deployment


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Line Connection

Alexander Kappes, Forschungsseminar, Humboldt-Universität, 11.02.2011cc

• Light scattering + chromatic dispersion: ~ 2 ns

• TTS in PMTs: ~ 1.2 ns

→ Intrinsic angular resolution 0.2˚– 0.3˚

Requires electronics + calibration: < 0.5 ns

Timing Calibration

Signal time in OMs relative to reference PMT

Alexander Kappes, Forschungsseminar, Humboldt-Universität, 11.02.2011cc

• Acoustic positioning system

• Tiltmeter and compass on each storey

Accuracy = 10 cm (0.5 ns)

Position Calibration

20 day periodMarch 2007

0 4-4-8-12 X [m]

-4

0

4

-8

Y [

m] Horizontal storey movement


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Optical Background

2005 2006 2007 2008

cable fault

2009

(Different colors correspond to different storeys)

Sin

gle

PM

T r

ate

[kH

z]

Optical background due to 40K decay and bioluminescence

• Typical rates 60-100 kHz per photomultiplier

• Occasional bursts and periods of high rates

Filtered by causality conditions between hits


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QuickTime™ and aGIF decompressor

are needed to see this picture.

Up-going Neutrino Candidate


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Selected Resultsfrom ANTARES


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Atmospheric Muons & Neutrinos

Up-going:ν-induced muons (~1000)

ANTARES (341 days)

Down-going:atm. muons


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Muon Intensity vs. Depth (90 days, 5 Lines):

2.5km6km Astropart. Phys. 34 (2010) pp. 179-184


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Upper Limit on Diffuse Flux (334 days)

IceCube 40 Strings

Physics Letters B 696 (2011) 16–22


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Full-Sky Search for Point Sources (295 days)

Most significant cluster

• Cluster of 8 events:Unbinned likelihood fit: Nsig = 5.16p-value = 0.024 (2.0 σ)

• Also no significant excess for selected sources

Equatorial coordinates


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Flux Limits and Sensitivity

25

preliminarypublication in preparation

Best limits on neutrino fluxes from southern-sky sources


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• Neutralino (χ) good WIMP candidate

• ANTARES data:No excess

Long term investigation necessary

Dark Matter Searches (WIMPs)

χ

ν

-ν

hard (W+W–)

soft (bb)ANTARES (5-line data, ~70 days)

preliminary

Neutralino mass [GeV]0 100 200 300 400 500 600 700

Φ(ν

μ+

νμ)

(>1

0 G

eV

) fr

om

Su

n [

km

-2 y

r-1]

109

1010

1011

1012

1013


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More Physics

Point sources:

• Gamma-ray bursts

• Flaring sources (e.g. AGNs)

• Use coincidences in neutrino telescopes to trigger optical follow-up

Other topics:

• Neutrino oscillations (atmospheric neutrinos 10 - 100 GeV)

• Exotic physics (Lorentz violation, monopoles, . . .)

• Cosmogenic neutrinos (E 10≳ 17 eV)

• Cosmic-ray anisotropy


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The Future Mediterranean

Neutrino Telescope KM3NeT


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Current Upper Limits on Point Sources

90% C.L. upper flux limits for E-2 spectra (preliminary)

⇒ km3-class detector in Northern Hemisphere needed

Galactic sources with TeV γ-ray emission


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KM3NeT

Artist’s view

• Future cubic-kilometer-class Mediterraneanneutrino telescope(joint effort of ANTARES, NEMO, NESTOR)

• Supported by ESFRI, ASPERA, ASTRONET

• Objectives:

- Exceed Northern-hemisphere telescopes by factor ~50 in sensitivity

- Exceed IceCube sensitivity by substantial factor

- Provide node for earth and marine sciences

- Budget: ~220 MEuro

EU-funded Design Study (2006–09) and Preparatory Phase (2007–11)


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Objective: Support 3D-array of photodetectors andconnect them to shore (data, power, slow control)

• Optical Modules

• Front-end electronics

• Readout, data acquisition, data transport

• Mechanical structures, backbone cable

• General deployment strategy

• Sea-bed network: cables, junction boxes

• Calibration devices

• Shore infrastructure

• Assembly, transport, logistics

• Risk analysis and quality control

Technical Design

Design rationale:cost-effectivereliableproducibleeasy to deploy


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OM with Many Small PMTs

• 31× 3” PMTs in 17-inch glass sphere(total ~140 mW)

• Front-end electronics (B,C)

• Al cooling shield and stem (A)

• Advantages:

- autonomous detection unit with single penetrator

- same photocathode area as 3 large PMTs

- directional information

- reduced afterpulsing

- improved 1-vs-2 photo-electron separation better sensitivity to coincidences⇒

A

B

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PMT


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• 20 storeys

• Each storey supports 2 multi-PMTs

• Power and data cables separated from ropes;single backbone cable with breakouts to storeys

• Distance between DU base and first storey = 100m

Flexible Towers with Horizontal Bars

2 km

Footprint “building block”(optimization ongoing)

• 2 “building blocks” required toachieve objectives


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Point Source Sensitivities (1 year)

ANTARES: 1 yr (pred. sensitivity)

Predicted fluxesHalzen, AK, O’Murchadha, PRD (2008)AK, Hinton, Stegmann, Aharonian, ApJ (2006)Kistler, Beacom, PRD (2006)Costantini & Vissani, App (2005) . . .

KM3NeT: 1 yr (pred. sensitivity)KM3NeT

IceCube 80: 1 yr (pred. sensitivity)

ANTARES

IceCube

90% CL sensitivity for E-2 spectra (preliminary)

• Vision of a worldwide neutrino observatory (IceCube + KM3NeT)

• Large overlap region (enhanced sensitivity + cross check)

SNR RX J1713 @ 5σ in 8 years


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Next steps: Prototyping and design decisions

• TDR public since June 2010

• final decisions require site selection

• expected to be achieved by end of 2011

Timeline:

Next Steps and Timeline

nownow

Feb

2006

Feb

2006

Mar

200

8

Mar

200

8

Jun

2010

Jun

2010

Mar

201

2

Mar

201

2

TDRTDRCDRCDR

Design StudyDesign Study

Preparatory phasePreparatory phase

Prototyping and constructionPrototyping and construction

Data takingData taking

2014

2014

2018

2018

Design and site decision

Design and site decision


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Summary

• Neutrino provide complementary information to gamma-rays and protons of the high-energy universe

• ANTARES completed since May 2008

- First results published and further analyses in full swing

- No deviations from background observed

- Detector likely too small to detect cosmic neutrinos

• KM3NeT: km3-class neutrino telescope in Northern Hemisphereneeded to complement IceCube

- In prototyping phase

- Substantially improved sensitivity compared to IceCube

- First data could be available in 2014

alexander kappes forschungsseminar institut für physik, humboldt-universität berlin, 11. february...

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