O.V. Vedeneev

Temporal structure of scintillation detector pulse in EAS

At the Moscow University EAS array the detector pulse shapes were observed with the help of two scintillation detectors of area 4 , each separated by 23 m. The pulse shapes were analysed in EAS with a particle density of more than 10 . 13 pulses were observed in the EAS with sizes at core distances R > 200 m. Some of the pulses have fine temporal structure with secondary peaks corresponding to tens of particles. Comparison of the individual experimental pulse shapes with the pulse shapes expected for the EAS particles arriving randomly due to the average time distribution indicates the non-statistical temporal structure of the pulses.

The EAS-1000 Array

The requirements for a newly constructed EAS array are summarized, and the EAS-1000 array now under construction is described. The array is depicted, and its accuracy in finding EAS parameters is shown. The expected statistics in observing EAS of different energies are presented for the most important scientific problems the array is supposed to solve.

The necessity and reality of EAS-1000 construction

The main problems of superhigh energy cosmic ray physics are discussed. It is pointed out that the existing EAS arrays can not improve the level of experimental research in the near future and the arrays of a new generation are very much needed. The short description of the constructed EAS-1000 array and its first stage EAS-100 is given.

Estimating primary mass composition at energies 1017–1018 eV from EAS radio emission lateral distribution

Distribution of maximum depths of extensive air showers (EAS) with energies of 1017–1018 eV is restored from the lateral distribution of EAS radio emission measured by the LOPES experiment (40-80 MHz). Dependence of the EAS maximum depth on its energy is constructed and mass composition of cosmic rays is estimated. It follows from the obtained dependencies that the fraction of light cosmic rays nuclei increases in the energy range under consideration.

The EAS-1000 array and perspectives of the primary mass composition studies at ultra-high energies

The status of EAS:-1000 array is presented. Considering the possibility of data acquisition on EAS muons and Cherenkov light the problem of CR mass composition investigations is discussed.