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The KASCADE-Grande Experiment: an Overview

The KASCADE-Grande Experiment: an Overview. Andrea Chiavassa Universita’ di Torino for the KASCADE-Grande Collaboration. Motivation for measurements 10 16 -10 18 eV. test of hadronic interaction models. KASCADE-Grande @Forschungszentrum Karlsruhe. Grande

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The KASCADE-Grande Experiment: an Overview

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  1. The KASCADE-Grande Experiment: an Overview Andrea Chiavassa Universita’ di Torino for the KASCADE-Grande Collaboration

  2. Motivation for measurements 1016-1018 eV • test of hadronic • interaction models

  3. KASCADE-Grande @Forschungszentrum Karlsruhe

  4. Grande 37 Stations of plastic scintillators 10 m2 each 140 m average distance 0.5 Km2 total surface 18 cluster 7/7 → 0.5 Hz → sent to KASCADE array detectors. Piccolo: fast trigger for the m tracking detectors

  5. KASCADE-Grande Trigger efficiency in a fiducial area of 0.28 km2 Including reconstruction cuts 100% reached at 2x1016 eV or 106 Shower Size Hydrogen Iron All Elements Hydrogen Iron All Elements

  6. KASCADE-Grande observables • Shower core and arrival direction • Grande array • Shower Size (Nch number of charged particles) • Grande array • Fit NKG like ldf • m Size (Em>230 MeV) • KASCADE array m detectors • Fit Lagutin Function • m density (Em>2400 MeV) • MWPC • m density & direction (Em>800 MeV) • Streamer Tubes

  7. Single Event

  8. 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.

  9. In each Shower size bin we obtain the distribution of the difference between the arrival directions measured by the Grande and by the KASCADE arrays DY = arccos(cos(qK)*cos(qG)+sin(qK)*sin(qG)+cos(FK-FG)) ) D arrival direction ( • Fitting a Rayleigh distribution • the angular resolution of • the Grande array is obtained • <0.7° Log Nch

  10. ( s core position (m) core position resolution s 5 m Log Nch

  11. events In each Shower Size bin we obtain the distribution of the difference between the Shower Size determined by the KASCADE and the Grande arrays (Nch,G-Nch,K)/Nch,K

  12. Grande Shower Size reconstruction accuracy ≤ 20%. Log Nch Shower Size systematic difference with KASCADE <5% Log Nch

  13. Lateral distributions of charged particles showing the good performance of the array 0 ° <q<18 °

  14. E>1017 eV 4300 events 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

  15. Way to all particle Energy Spectrum:1) Constant Intensity Cut Method (Nch or Nm) Integral Flux I(>Nch) Log Nch • Integral spectra measured in • different bins of zenith angle • 2) For a given I(>NX) → NX(q) 3) Get Attenuation Curves

  16. 4) Nch,m(q) → Nch,m(qref) 5) Nch,m(qref) is converted to primary energy Influence of: interaction models, MC statistics, slope used in the simulation Energy Spectrum measurements starting from different observables. Cross checks & Systematics A first study of the systematic (Nm) uncertainties has been performed For E 1017 eV → DE 22%

  17. 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

  18. 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 log10(E)=a(k)log10(Nch)+b(k) k=f(Nch/N,Nch) H Fe Number of Events from the ratio of reconstructed/true flux: systematic difference (different primaries) <5% for E>1016 eV original reconstructed Log E(GeV) Log E(GeV) From the bin to bin fluctuations Uncertainty ≤15% for E>1016 eV

  19. First Results from KASCADE-Grande (ICRC 2007) Anisotropy • 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.

  20. 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

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