Convergence to GZK prediction in UHE measurements of the primary energy spectrum of cosmic rays J. N. Capdevielle, APC, University Paris Diderot [email protected]

Convergence to GZK prediction in

UHE measurements of the primary

energy spectrum of cosmic rays

J. N. Capdevielle, APC, University Paris [email protected]

OutlineOutline General properties of giant EASGeneral properties of giant EAS The extrapolation at UHEThe extrapolation at UHE The treatment of inclined GAS in AGASAThe treatment of inclined GAS in AGASA The treatment of the vertical energy The treatment of the vertical energy

estimatorestimator Amendments of experimental data and Amendments of experimental data and

general convergence to GZK predictiongeneral convergence to GZK prediction Mass composition at UHEMass composition at UHE

Propagation : coupure GZKGreisen, Zatsepin, Kuzmin

Interaction des hadrons avec le fond de photons à 3K (CMB)

Eseuil = 70 EeV

protons

Les sources doivent être proches !

Individual showersIndividual showers

Differential Primary Energy Spectrum of Cosmic Rays

Isotropic distribution of sources

1 = 500 g/cm2 2 = 594 g/cm2

AGASA conversion 600 600

Treatment of inclined EAS data from surface arrays and GZK prediction

Jean Noël CAPDEVIELLE, F.COHEN, B.SZABELSKA, J.SZABELSKI

Measured: lateral distribution + direction (θ, φ)

Density (600m, θ) Density(600m, 0) Energy

That conversion is energy/size independent

See J.phys. G 36 (2009) 075203 by J.N.Capdevielle., F. Cohen, B. Szabelska and J. Szabelski for detailed treatment of inclined EAS



Results of CORSIKAsimulations showcomplicatedand energy dependentform

example:

Conversion to ''vertical density''



Cascade theory and CORSIKA simulations

results for the highest energies depend on interaction model,but suggest overestimation of energy at AGASA



From Bergman spectrum to AGASA spectrumusing AGASA conversion

Grey area: D.R.Bergman et al. (HiRes Collaboration) 29th ICRC, Pune, India, 2005

Red points: AGASA energy spectrum

histograms:MC generated spectrum following Bergman approximately recalculated spectrum using AGASA conversion



How does the conversion to ''vertical density'' work ?


• The spectrum from surface array has to be corrected from the overestimation of the primary energy between 10°-35° in the last decade

• the amended spectrum of AGASA (ISVHECRI aug. 06) is progressing in this direction

• The overestimation in AGASA data was coming up to 50% (in reason of the maximum depth given by AUGER) of the special properties of 3D Electromagnetic cascade near maximum

• It could be more for a pure proton component and less in case of a heavy composition

Fluctuations at constant Fluctuations at constant primary energyprimary energy

100 EeV100 EeV

80 EAS80 EAS

Left wing dominated by the effect of cross section

Same EAS taking into account axis localization ( +/-30m)

and density measurement (10% error)

Knee turns from 3 to 5, ankle 3to 2

Statistical knee effect, decreases the population of high energy EAS in the right wing-- Lower <Eo>

Energy Overestimation

Statistical ankle effect , larger population of EAS in right wing- larger <Eo>

Energy Underestimation

Distribution of Energies contributing to S600= 300

Conversion S600 Eo dashed curve both spectra error on axis of 30m, lower curve 50m, 10% on density

Corrections for 11 of the most energetic cascades in AGASA

AGASA (squares), AUGER(discs), HIRES(stars)

EUSO ~ 1000 x AGASA ~ 30 x AugerEUSO (Instantaneous) ~ 5000 x AGASA ~ 150 x Auger

AGASA

JEM-EUSO tilt-mode

JEM-EUSO FoVJEM-EUSO FoV

Principle of EUSOPrinciple of EUSO- first - first remote-sensingremote-sensing from space, opening a new from space, opening a new

window for the highest energy regimewindow for the highest energy regime

From College de France: better data now

TPC-likenaturalchamber

Cf: Ground-based arrays < 100 EUSO(1) Scintillator array,(2)Fluorescence telescope array

1020 eV

ConclusionsConclusions The primary energy measured in giant surface arrays may be

overestimated in two steps.:

1/ conversion of inclined density S600 to vertical density of reference without taking into account the behavahiour of the estimator versus zenith angle when the maximum depth is close of the level of the array

2/ conversion of the vertical density to the primary energy without taking into account the statistical disturbances generated by a knee in the differential primary spectrum

When corrected for both procedures, AGASA data reflects a GZK behaviour of the primary energy spectrum of cosmic rays in agreement with HIRES and AUGER.

PerspectivesPerspectives New chances for Proton &Gamma ray

Astronomy at UHE from ISS with JEM-EUSO

New results of LHC updating the simulation

. Xmax behaviour and change in p-Air

interaction above 3 EeV? Ratio of light at 500g/cm2 to 1100g/cm2

depends on mass (in favour of p composition at UHE for HIRES)

G.COCCONI, 1961

Ne

t

e

r

Cascade électromagnétique Cascade électromagnétique (NKG)(NKG)

Trans GZK AREATrans GZK AREA New scales New scales Adequate Adequate

Advanced Advanced TechnologiesTechnologies

Milesbornes to Milesbornes to Quantum GravityQuantum Gravity

earliest earliest approaches, EUSO approaches, EUSO and JEM-EUSOand JEM-EUSO

Astronomie proton

1000 evts à répartir sur un certain nombre de sources éventuelles avec leur spectre respectif

Fonction Gaussienne hypergéométrique

f(x) = Ne x s-a (1+x) s-b(1+d.x)-c

À angle fixe, il va falloir ajuster les paramètres :a, b, c, r0, r1, , , , r’0 et r’1

Ne , N et “s” sont donnés par la simulation

Avec x = r / r0 et d = r0 / r1Électrons

Muons f(x) = N x - (1+x)-(-)(1+.x)-

Avec x = r / r’0 et = r’

0 / r’1



Georgi Timofeevich Zatsepin (2006)

Vadim Alekseyevich Kuzmin (2006)

Résultats des Résultats des ajustementsajustements

Résultats des Résultats des ajustementsajustements

Xmax (g/cm2) and Nmax Xmax (g/cm2) and Nmax for p, Fe initiated showersfor p, Fe initiated showers

Documents

Convergence to GZK prediction in UHE measurements of the primary energy spectrum of cosmic rays J. N. Capdevielle, APC, University Paris Diderot [email protected]