MAKET-ANI is an extensive air shower experiment array to study the cosmic ray primary flux in the ‘knee’ region of the primary cosmic ray spectrum. The MAKET-ANI detector is placed on Mt. Aragats (Aragats Cosmic Ray Observatory, Armenia), 3200m above the sea level at 40°25’N, 44°15’E operating at an atmospheric depth of ~700g/cm². At this altitude, the shape of the showers is not distorted by the attenuation in the terrestrial atmosphere and it is possible to reliably reconstruct EAS size and shape.

The MAKET-ANI surface array (see fig.'Maket-Ani Setup) consists of 92 particle density detectors formed from plastic scintillators with a thickness of 5 cm. Twenty-four of them have an area of 0.09m² and 68 an area of 1m². The central part consists of 73 scintillation detectors and is arranged in a rectangle of 85x65 m². Two peripheral points at a distance of 95 m and 65 m from the centre of the installation consist of 15 and 4 scintillators, respectively.

Fig.: 'Maket-Ani Setup' - Schematic view of the Maket-Ani array.

Fig.: 'Maket-Ani' at Mount Aragats

During multiyear measurements, the detecting channels were continuously monitored. Data on background cosmic-ray spectra was collected for each detector. The slope of the spectra was used for detector calibration. The slope of background spectra is a very stable parameter and does not change even during very severe Forbush decreases, when the mean count rates can decrease as much as 20%.

The 'all particle spectrum' obtained with the Maket-Ani detector system is shown in the figure 'all particle spectrum by Maket-Ani' and can be downloaded from the KCDC 'Spectra' page.

Fig.: 'all particle spectrum by Maket-Ani'

For further details contact the homepage of the Cosmic Ray Division of Yerevan Physics Institute