The KASCADE-Grande Experiment: an Overview

Andrea ChiavassaUniversita’ di Torino

for the KASCADE-Grande Collaboration

Motivation for measurements 1016-1018 eV

- test of hadronic interaction models

DetectorDetector Detected EAS Detected EAS componentcomponent

Detection TechniqueDetection Technique Detector Detector area (marea (m22))

GrandeGrande Charged particlesCharged particles Plastic ScintillatorsPlastic Scintillators 37x1037x10

PiccoloPiccolo Charged particlesCharged particles Plastic ScintillatorsPlastic Scintillators 8x108x10

KASCADE array KASCADE array e/e/

Electrons, Electrons, Liquid ScintillatorsLiquid Scintillators 490490

KASCADE array KASCADE array

MuonsMuons (E(Ethth=230 MeV)=230 MeV)

Plastic ScintillatorsPlastic Scintillators 622622

MTDMTD Muons (Tracking) Muons (Tracking) (E(Ethth=800 MeV)=800 MeV)

Streamer TubesStreamer Tubes 4x1284x128

MWPCs/LSTsMWPCs/LSTs Muons Muons (E(Ethth=2.4 GeV)=2.4 GeV)

Multiwire Proportional Multiwire Proportional ChambersChambers

3x1293x129

LOPES 30LOPES 30 RadioRadio Radio Antennas (40-80 Radio Antennas (40-80 MHz)MHz)

 

KASCADE-Grande@Forschungszentrum Karlsruhe

Grande37 Stations of plastic scintillators10 m2 each140 m average distance0.5 Km2 total surface

18 cluster 7/7 → 0.5 Hz → sent to KASCADE array detectors.

Piccolo: fast trigger for the tracking detectors

KASCADE-GrandeTrigger efficiency in a fiducial area of 0.28 km2

Including reconstruction cuts100% reached at 2x1016 eVor 106 Shower Size

HydrogenIronAll Elements

HydrogenIronAll Elements

KASCADE-Grande observables• Shower core and arrival direction

– Grande array• Shower Size (Nch number of charged particles)

– Grande array• Fit NKG like ldf

• Size (E>230 MeV)

– KASCADE array detectors• Fit Lagutin Function

• density (E>2400 MeV)

– MWPC• density & direction (E>800 MeV)

– Streamer Tubes

Single Event

The resolution of the Grande array is obtained comparing the Grande event reconstruction with the one of the KASCADE array.

Similar results are obtained reconstructing simulated events.Covering a wider shower size range and the whole detector area.

In each Shower size bin we obtain thedistribution of the difference betweenthe arrival directions measured by theGrande and by the KASCADE arrays

Fitting a Rayleigh distributionthe angular resolution ofthe Grande array is obtained

<0.7°

arrival direction ( )

Log Nch

= arccos(cos(K)*cos(G)+sin(K)*sin(G)+cos(K-G))

22 )()( GKGK yyxxr

core position resolution 5 m

co

re p

osit

ion

(m

)

(

Log Nch

In each Shower Size bin we obtainthe distribution of the differencebetween the Shower Size determinedby the KASCADE and the Grande arrays

Kch

KchGch

N

NN

,

,,

(Nch,G-Nch,K)/Nch,K

even

ts

Grande Shower Sizereconstruction accuracy

≤ 20%.

Shower Size systematic differencewith KASCADE <5%

Log Nch

Log Nch

Lateral distributions of charged particlesshowing the good performance of the array

0 ° <<18 °

Unfolding of 2-Dimensional shower size spectra, in different bin of zenith angle, will allow studies of energy & composition→ still improvements in systematics needed→ higher statistics

E>1017 eV4300 events

Way to all particle Energy Spectrum:1) Constant Intensity Cut Method (Nch or N)

1) Integral spectra measured in different bins of zenith angle

2) For a given I(>NX) → NX()

Log Nch

Inte

gral

Flu

x I(

>N

ch)

3) Get Attenuation Curves

A first study of the systematic (N) uncertainties has been performed

For E 1017 eV → E 22%

Energy Spectrum measurementsstarting from different observables.

Cross checks & Systematics

5) Nch,(ref) is converted to primary energy

Influence of: interaction models, MC statistics,slope used in the simulation

4) Nch,() → Nch,(ref)

Way to all particle Energy Spectrum:2) Energy reconstruction by S(500)

S(500) chosen as energy estimator

Event by event determination of S(500)Correction to a reference angle

S(500) is converted to primary energy

Way to all particle Energy Spectrum:3) Primary energy estimated event by event

• Nch (or N) as primary energy estimator

• Log(Nch/N) as mass and shower fluctuation estimator

From the bin to bin fluctuationsUncertainty ≤15% for E>1016 eV

from the ratio of reconstructed/true flux:systematic difference (different primaries)

<5% for E>1016 eV

log10(E)=a(k)log10(Nch)+b(k)

k=f(Nch/N,Nch)

H Fe

originalreconstructed

Log E(GeV)Log E(GeV)

Nu

mb

er o

f E

ven

ts

First Results from KASCADE-Grande (ICRC 2007)

• Limits obtained with 1/3 of the available statistics are already significative.

• KASCADE-Grande results will play a relevant role in the evaluation of the anistropies in the knee region.

Anisotropy

Conclusions

• KASCADE-Grande is measuring in the 10-1000 PeV energy range since January 2004

• Experiment performances:

– angular resolution <0.7°

– core resolution 5m

– Shower size resolution ≤20%

• Energy Spectrum and Primary composition studies are on the way