W. HofmannMPI für KernphysikHeidelberg

Instrumentation forAstroparticle Physics

Grav. waves

Axions

Mono-poles

Electromagneticradiation -> 100 TeV

Cosmic rayparticles -> 1020 eV

Neutrinos(MeV: sun, SNGeV: atmospherePeV: CR accerators)

Dark matter

State of the field: a charming infant

Radio

Optical

UV

X-Ray

Gamma

IR

1

100

10000

1000000

100000000

101210610010-6

Energy [eV]

Peak detected fluxDetection threshold

Neutrinos (?)1

10

100

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1960 1970 1980 1990 2000 2010

Num

ber

of s

ourc

es

Year

Gamma (GeV)

Gamma (TeV)

Uhuru

Einstein

Ginga

Rosat

CGRO

COS-B

SAS-2

GLAST

Cherenkovtelescopes

X-Ray (keV)

Radio

Optical X-Ray

Gamma

100

101210610010-6

Energy [eV]

Angular resolution [degr.]

10-2

10-4

10-6

Neutrinos

Fluxsensitivity

Fluxsensitivity

Angularresolution

Angularresolution

Numberof sources

Numberof sources

Astrophysicswith gamma raysand neutrinos

Astrophysicswith gamma raysand neutrinos

Gamma rays and cosmic rays

Electromagneticradiation -> 100 TeV

Cosmic rayparticles -> 1020 eV

The big issues in cosmic-ray physics

• at low (GeV – TeV) energy: antiparticles in cosmic rays? AMS• at medium (PeV) energy elemental composition, change in composition at knee? (KASKADE,…)• at high (EeV) energy spectrum, particles beyond GKZ cutoff? AUGER

• Sources of cosmic rays traced in the light of (secondary) gamma rays

-yield = CR density x target density EGRET~ 100 MeV

eV

Propagation of electromagnetic radiation

In the Earth’satmosphere

In space

Horizondue to inter- actions

100

101102

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107108

1010 1011 1012 1013 1014 1015 1016 1017R

ange

[kpc

]E [eV]

Size of Milky Way

Nearest galaxy

Mkn 501

Gam

ma r

ay

X-R

ay

Ult

ravio

let

Infr

are

d

Radio

Sea level

500 km

100 km

10 kmV

isib

leAir shower Fluorescence light Radio waves Cherenkov light Particles at ground level

similar effect: Cosmic-ray propagationcuts off at 1020 eV

GeV/TeV CR: Alpha Magnetic Spectrometer

AMS-01 (1998) AMS-02 on ISS

GLAST: -rays in the GeV energy range

Che

renk

ov-L

ight

Image of the shower in the PMT camera

Effectivedetection area:~ 50000 m2

~ 120 m

~ 120 m

VHE air shower detectors: Cherenkov telescopes

100 photons/m2 TeVwithin a few ns

~ 1o

ImageOrientation shower directionIntensity energy of primaryShape type of primary

Telling -rays from hadronic cosmic rays

p (?)

p (?)x x

x x

z z

y y

The imaging atmospheric Cherenkov technique

Pioneered by theWHIPPLE group

Perfectioned in CAT telescope

WHIPPLE490 PMTcamera

Stereoscopywith HEGRA

Four eyes see better than one: H.E.S.S. (and VERITAS, CANGAROO, …)

12 m Cherenkov telescopesunder construction in Namibia

Combine Stereoscopy from HEGRA telescopes• improved angular resolution• enhanced background suppressionTrigger and fine pixels from CAT telescopesMonitoring from Durham telescopes

• 100 m2 mirror• 15 m focal length• 960 PMT camera• 1 GHz analog pipeline• 50 GeV threshold• 10 times improved sensitivity cf. HEGRA

Source hunting with MAGIC

• 17 m dish, 220 m2 active mirror• low weight fast positioning• high-speed optics and electronics• initial PMT camera• later GaAsP and APD detectors 10 GeV threshold

Aluminum mirrors

PMT with hemispherical windowand optical signal transmission

Sensitivity and limitations of the technique

Angular resolution, cosmic-ray rejection limited by• Shower fluctuations• Earth magnetic fieldAlso, light yield depends on height!

Angular resolutionfor “ideal” detector

Side view of shower

Irreducible background• Cosmic-ray electronscan only be discriminated on the basis of shower direction.

Hard to go beyond mCrabsensitivities with the imaging Cherenkov technique …

Better vision – novel photon detectors

0

500

1000

1500

2000

2500

0 5 10 15 20 25

Co

st [

Eur

o]

Dish diameter [m]

Cost of dish

Cost of camera

Better photon detectorsfor Cherenkov telescopes• allow large savings• improve performanceneed m2 cathode area …

~ 15%

~ 22%

~ 62%

• Hybrid PMTs• GaAsP limited to few 100 mm2

• Si (APD) even smaller, QE below CCD

An alternative approach: non-imaging detectors

STACEE

Large mirror area and hencelow energy threshold

Poor cosmic-ray rejectionSignificant learning curveCELESTE sees Crab at 50 GeV

Competitive in the long run?

CELESTE secondaryreflector and PMTs

Tail catchers: particle detectors

Tibet air shower array(Scintillators)

Milagro, Los Alamos(Water Cherenkov)

ARGO,Tibet(RPC array)

High altitude andlarge area coverage

Avantages• large solid angle • 100% duty cyleDisadvantages• TeV+ threshold• marginal (Crab-level) sensitivityComplementary to Cherenkov telescopes planned

The ultimate experience: AUGER

Air shower detector• 3000 km2 area• two detector technologies particle detectors fluorescence telescopes• ~ 20000 events > 1019 eV• ~ 100 events > 1020 eV

1600 detectors1.5 km spacing

AUGER fluorescence detectors

AUGER performance

Detection area

Simulated spectrum

The view from above: OWL

Threshold: 1019-1020 eVEff. area: few 106 km2sr

CR

106 pixel focal planeflat panel PMTs ? > 50o field of view

Neutrinos(MeV: sun, SNGeV: atmospherePeV: CR accerators)

High-Energy Neutrino Astrophysics

Proton accelerators generate roughly equal numbersof gamma rays and neutrinos !

• Neutrinos are not absorbed in sources; they escape even from strong sources• Neutrinos do not interact during propagation

Background: atmospheric neutrinos

Signal from cosmic accelerators

Scientific AmericanExtreme Engineering Issue

Seven wonders of modern astronomy• The sharpest• The biggest• The farthest flung• The most extensive• The swiftest• The deadliest• The weirdest: AMANDA at the south pole

AMANDA II (2000)

4 strings

10 strings

19 strings, eff. area ~ 5x104 m2

Detection: Cherenkov light in water / ice

1 km deep under water / ice

ICE CUBE,ANTARES:1000000000 m3

~ 5000 PMTsThreshold ~ 1 TeV

Key difference:

Ice / AMANDA II: ~ 100 m absorption length, ~ 20 m scattering length diffusive component angular resolution 1.2o

Water / ANTARES, NESTOR ~ 60 m absorption length, ~ 200 m scattering length angular resolution 0.2o

Instrument R&D

• Optical module design• Deployment schemes• PMTs• Signal transmission• Digital modules

Module withoptical signaltransmission(AMANDA)

ARS 1 GHz analog ring sampler ASICwith digital signalprocession(ANTARES)

ANTARESDemonstrator

AMANDA at the South Pole

-Sky (AMANDA ’97)

ICECUBE

80 “Strings” of 60 PMTsin 1400 – 2300 m depth

Physics issues (ICECUBE, ANTARES, NESTOR):- neutrinos from CR accelerators- neutrinos from DM annihilation- atmospheric neutrinos, oscillations- magnetic monopoles- galactic supernovae- …

Solar neutrinos

Super-Kamiokande:the neutrino image of the sun

Detectors for solar (MeV) neutrinos

BOREXINO,KAMLAND(2):Liquid Scintillator

SuperKamiokandeWater Cherenkov

e

e

e

D p p

e

SNO: Heavy-Water Cherenkov

e

e

LENS:Liquid Scintillatorwith “Tag”

Yb Lu*

e e

pp

Be

pep

50 ns

-flavor no (NC) yes (CC) no (NC) yes (CC)-energy res.poor good poor goodthreshold 4-5 MeV 4-5 MeV 1 MeV 0.3 MeV

Alternative techniques

HERON: superfluid He;evaporation by photons/rotonsand scintillation

ICARUS: liquid argon DC

HELLAZ: TPC

air shower

delta-ray

Darkmatter

The dark side of the universe

CMB (Boomerang, Maxima)High-z Supernovae, BBN

~ 1.0M ~ 0.2-0.3B ~ 0.03 – 0.05

most matter is dark, nonbaryonic

Particle physics candidates, e.g.WIMPs, accumulate in the halo of galaxies (local density 0.3 GeV/cm3)

Searching for WIMPs

Principle: elastic scattering on nuclei

Typ. recoil: a few 100 eV / GeV WIMP massTyp. rate: a few events / kg / day

)cos1()( 2

2

Mm

Mmvm

W

WWRE

WIMPRecoil

Phonons

Ionization

Light