In 1997 the MAKET-ANI surface array in Armenia was launched in its full configuration with ~100 plastic scintillators of 1 m2 area each, viewed by photomultipliers. The efficiency of extensive air shower core selection from surface of ~1000 m2 around geometrical center of the array was above 95% for EASs generated by primary particles with energy ≥5x1014 eV. The compact array with well calibrated detectors turned out to be very well suited for the energy and composition measurements at the “knee” of the cosmic ray spectrum.

More than a million EASs detected in 1999-2004 have been carefully examined and used for the estimation of energy spectra of light and heavy nuclei (Chilingarian et al, 2004). Using thenon-parametric multivariate methodology of data analysis (Chilingarian1989), the problemof event-by-event classification ofEAS has been solved (Chilingarian &Zazyan 1991) using Bayesianand neural network techniques (Chilingarian et al., 2004, Chilingarian et al., 2007).  


maket picture



Figure 1The output of the Neural Network trained to distinguish “light” and “heavy” nuclei (from Chilingarian et al., 2004).

maket picture1

Figure 2Energy spectra of light and heavy nuclei obtained by neural classification and energy estimation. The EAS characteristics used are shower size and shape (age parameter).

     The evidence from MAKET-ANI data can be summarized as follows:

  1. The estimated energy spectrum of the light mass group of nuclei shows a sharp knee:   0.9, compared to 0.3 for the all-particle energy spectra.
  2. The energy spectrum of the heavy mass group of cosmic rays shows no break in the energy interval of 10152x1016 eV. 
  3. The MAKET-ANI results on the rigidity-dependent position of knee, points towards SNRs as most favorable sources of galactic cosmic rays and Fermi-type acceleration as the mechanism of hadron acceleration. Further results from KASCADE array and the AGILE and Fermi orbital gamma ray observatories, as well as several theoretical extensions of Fermi mechanism confirms MAKET-ANI results. 



Chilingarian A. A., Statistical Decisions under Nonparametric a priori information, Computer Physics Comunication, 54, 381, 1989.

A.Chilingarian, G.Zazyan, On the possibility of investigation of the mass composition and energy spectra of primary cosmic ray (PCR) in the energy range from 1015 to 1017 eV using EAS data, Nuovo Cimento C, Serie 1 (ISSN 0390-5551), vol. 14 C, Nov.-Dec. 1991, p. 555-568,

A.Chilingarian , G. Gharagyozyan , G. Hovsepyan , S. Ghazaryan , L. Melkumyan , and A. Vardanyan , Light and Heavy Cosmic Ray Mass Group Energy Spectra as Measured by the MAKET-ANI Detector, Astrophysical Journal, 603:L29-L32, 2004, 

A.Chilingarian , G. Gharagyozyan , G. Hovsepyan , S. Ghazaryan , L. Melkumyan , A. Vardanyan, E.Mamidjanyan, V.Romakhin,  and S. Sokhoyan Study of extensive air showers and primary energy spectra by MAKET-ANI detector on Mount Aragats, Astroparticle Physics, Volume 28, Issue 1, September 2007, Pages 58–71