Pierre AUGER Observatory

Jan RidkyInstitute of Physics AS CR

ridky@fzu.cz

For Pierre Auger collaboration

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astro-particle physics

• spectrum• sources• anisotropy• acceleration• composition• ……

Mission of Pierre Auger Observatory:

• spectrum• interactions• X-sections (p-Air )• acceleration• neutrinos• ….

• spectrum & MC

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Energy spectrum (a one-century quest!)

1 part/m2/s

Limit forsatellites

knee:1 part/m2/year

32 o

rders

of

magnit

ude!

12 orders of magnitude!

ankle : 1 part/km2/century!

Is there any end?

What kind of end if any?

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The Auger Collaboration

15+2 Countries 60+ Institutions 350+ Scientists

Argentina Netherlands

Australia Poland

Bolivia(*) Portugal

Brazil Slovenia

Czech Republic Spain

France United Kingdom

Germany USA

Italy Vietnam(*)

Mexico (*) Associate countries

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Pierre Auger Observatory

1 600 detectors 3 000 km2 area1.5 km spacing

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Pierre Auger Observatory

Hybrid detector

combined virtues ofsurface detector andfluorescence detector

2 independent measurements • cross-calibration• energy and directions• composition

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4 stations with 24 fluorescence telescopes- each station 180° field of view

CLF

LOMA AMARILLA

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Pierre Auger observatory - FD

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Pierre Auger observatory - FDFD = fluorescence detector

mirror: R = 3440 mmarea: 3,6 x 3,6 m2

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Observatoř Pierra Augera - SDPierre Auger observatory - SD

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communication antenna

electronics enclosure solar panels

battery box

3 – nine inchphotomultipliertubes

plastic tank with 12 tons of water … 12 m3

GPS antenna

white diffusion liner

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1285 tanks deployed … as of February 23/07

1256 with water

1155 with electronics

1600 tanks in total…beginning of2008

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Auger today

exposition ~ 5000 km2 y srin total ~ 5·105 events104 above 3·1018 eV – fully efficient SD(combined FD + SD …. energy ~ > 3·1017 eV)

photon limit

GC anisotropy

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Energy reconstruction (zenith < 60 deg)

“MC free” as much as possible

SD measurement calibrated by FD energy

…SD measures S(1000) = signal 1000 m from center - choice of “1000” based on MC . . LDF is measured ! !

…FD – calorimetric measurement of energy - invisible energy estimated by MC

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Energy . . . . reconstruction

energy reconstruction – S(1000) defined as LDF value 1000 m from impact of shower axis . . . . why 1000 ?

p Fe

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signal unit ~ 1 VEM

vertical equivalent muon

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Energy . . . . reconstruction

uncertainty of S(1000) due to signal fluctuation

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Energy . . . . reconstructionS(1000) of p and S(1000) of Fe …

fluctuations

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FD versus SDattenuationS(1000) -> S38(1000)

M. Roth, M. Unger, …

Constant Intensity Cut

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Pierre Auger observatory - FDFD can see up to 25 - 30 kmlaser calibration, atmosphere monitoring, . . .

stereo events -Čerenkov subtraction

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FD ….. fluorescence yieldexperiment AIRFLY . . .

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X – differences to US-Std. in III/05

Atmospheric monitoringAtmospheric monitoring

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reversal of the standard SD energy reconstruction

check of MC

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Events

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Events

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Lateral Distribution Function Fit

Surface Array view

Core distance (m)

Tan

k s

ign

a l (

VE

M)

Wed Mar 3 15:05:09 2004Easting = 477567 ± 21 m

Northing = 6084561 ± 25 mdt = 92.0 ns

Theta = 63.5 ± 0.1 degPhi = 72.1 ± 0.1/sin(Theta) deg

R = 24.2 ± 0.8 km

S(1000) = 86.46 ± 2.69 VEME = 59.44 EeV ± 3%

(stat. error only)PRELIMINARY

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PRELIMINARY analysis shows

zenith angle 64º, energy 59 EeV

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reversal of the standard SD energy reconstruction

check of MC

not enough muons !!!

Muons . . .

direct – fromheavy flavours

indirect – mainly from, K decays

Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

Typical high multiplicity event

RUN 107634, EVT 4731

Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

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Events . . . . even more inclined one

B

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Conclusions:

• Auger – South close to completion (early 2008)

• the technical parameters of PAO will allow unprecedented measurements in terms of statistics (area) energy (size of SD) pointing (FD angular resolution < 1 deg) composition (good atmospheric monitoring) precision (hybrid approach)

• valuable contribution to HEP . . . . in synergy with LHC – MC tuning

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supporting slides

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3 PMTs XP1805d1 Photonis read-out• last dynode – 1 FADC• anode – 1 FADC

40 MHz15 bits dynamic range (5 bits overlap)

most frequent signals are those of atmosphericmuons . . . . . . they are used for monitoring and calibration

~ 1 ÷ 1000 particles/μs

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Trigger T3. . . events

timing of signals(to beat accidentals)

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Trigger T3. . . events

timing of signals(to beat accidentals)

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Trigger T3. . . events

~ 0.02 Hz

T3 triggers

• 3ToT . . efficient trigger ~ 90% selected events mostly ‘vertical’ showers

• 4-fold coincidence of tanks within 6 km - essential for horizontal showers, more noisy

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Trigger T3. . . events

- 3ToT - 4C1

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Triggering events

trigger probability of a single tank - measured by a pair of close tanks

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Triggering events

- Threshold or ToT

- Threshold only

1018 eV

1020 eV

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T3 0 : 30 : 98% for 1 : 3 : 10 EeV zenith angle < 45°

Triggering events

LTP and LDF deduced from experiment by means of close tanks

NKG formula

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Events

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Events

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Events

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Events . . . . reconstructionuncertainty of S(1000) due to core location

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Events . . . . reconstructionuncertainty of S(1000) due to missing tank

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Events . . . . reconstruction

uncertainty of S(1000) due to: • statistical uncertainties at S(1000) ~ 30 VEM this corresponds to ~ 5·1018 eV are ~ 10%• due to LDF form < 4%• due to shower to shower fluctuations ≤ 10%• event sampling (missing tank ≤ 10%)

at ~ 3·1018 eV the surface array fully efficient-trigger efficiency, pressure & temperature dependence

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1.5 km

1.5 km

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Pierre Auger observatory - FD

diaphragm

filter 300 - 400 nm

mirror

fail-safe curtain

camera - 20 x 22photomultipliers 2,6”

Saturated event

… we have 6 such cases

Jan Ridky, ISVHECRI, Pylos, Greece, 6-12 Sept. 2004

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Photon limit

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Photon limit