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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
1000
10000
100000
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
103104
105106
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