"STRANA" (LPI) - processing and analysis of the unique gamma-hadron family with all-particle energy of 2*10^16 eV. The event was registered in LPI balloon-borne stratosphere experiment at the altitude of 30 km in 1975 and named after Prof. N.A.Dobrotin.

The figure shows the image of the gamma-hadron family registered by the X-ray film in emulsion chamber calorimeter. The family consists of 107 secondary particles with 76 gamma-quanta, 30 hadrons and one leading particle, and shows up a whole spectrum of interesting peculiarities.

Employing the PAVICOM facility, the nuclear emulsion plates containing the superfamily STRANA were processed. More then 800 family showers were processed in 8 nuclear emulsion layers of the emulsion chamber gamma-block. The goal of these high-accuracy measurements was to estimate the altitude of the primary particle interaction point above the chamber. The triangulation procedure was used. The data are still under processing.

Until recently, a profound analysis of this family was impossible bacause of the lack of appropriate measuring technique. The PAVICOM processing is expected to gain an insight into the nature of the event by means of:

  • determination of the interaction and primary particle energies;
  • analyzing the secondary particle distributions at the target plane in purpose of singling out the two qualitatively opposite effects: particle alignment near the shower core (azimuth asymmetry limit case for "fast particles"), and a circle-like structure of the shower outlying area (azimuth symmetry limit case for "slow particles");
  • recognizing the circle structures formed by the "slow particles" on the shower outlying area.

The further event treatment and analysis of its characteristics will elucidate the registered event nature to verify or not the hypotheses of double semi-hard inelastic diffraction and nuclear matter collective excitations.