Author/Authors :
Mohanty، نويسنده , , P.K. and Dugad، نويسنده , , S.R. and Goswami، نويسنده , , U.D. and Gupta، نويسنده , , S.K. and Hayashi، نويسنده , , Y. and Iyer، نويسنده , , A. and Ito، نويسنده , , N. and Jagadeesan، نويسنده , , P. and Jain، نويسنده , , A. and Karthikeyan، نويسنده , , S. and Kawakami، نويسنده , , S. and Minamino، نويسنده , , M. and Morris، نويسنده , , S.D. and Nayak، نويسنده , , P.K. and Nonaka، نويسنده , , T. and Oshima، نويسنده , , A. and Rao، نويسنده , , B.S. and Ravindran، نويسنده , , K.C. and Tanaka، نويسنده , , H. and Tonwar، نويسنده , , S.C.، نويسنده ,
Abstract :
The GRAPES-3 extensive air shower (EAS) array started operation with 256 scintillator detectors at Ooty in India. Each detector is viewed by a fast photomultiplier tube (PMT) mounted at a height of 60 cm above the scintillator. However, for further expansion of the array, an alternative readout of the scintillator using wave-length shifting (WLS) fibers is employed. This resulted in improved performance with a larger photon signal and a more uniform response. With the inclusion of a second PMT, the dynamic range for particle detection has been increased to ∼5 × 103 particles m−2. We now use plastic scintillators, developed in-house to cut costs. The measurement of the density spectrum, shows a power law dependence with an index γ = 1.57 ± 0.04. Using the zenith angle dependence of the density spectrum, an attenuation length Λa = 98–106 g cm−2 for the EAS is obtained. These measurements are found to be consistent with the results reported earlier by other groups.
Keywords :
Cosmic rays , Extensive Air Shower , scintillation detector , Particle detector
