T.I. Sysoeva

The results from ten years of measuring several parameters of the antarctic atmosphere with tethered balloons

The results from measuring several parameters of the Antarctic atmosphere’s lower layers over the period 2004 through 2014 (Russian Antarctic expeditions 49 through 59) are presented. Such atmospheric parameters as the altitude dependence of the velocity and direction of the ground wind, the level of background radiation, and the concentrations of ozone and singlet oxygen are studied. Devices are installed on board the vessel Akademik Fedorov and at Antarctic ground stations. Tethered balloons are also used.

Investigation of SPHERE-2 data sensitivity to chemical composition of primary cosmic rays

A new method for assessing the type of particles of primary cosmic rays in the energy range of 10–1000 PeV for individual events recorded by the SPHERE-2 facility is presented. The method is based on comparing images of recorded events and simulated events, while assuming various types of primary particles with allowance for measuring errors. The aim of the study is to find the limits of sensitivity in determining of the chemical composition of ultrahigh-energy primary cosmic rays using the detection of reflected Cherenkov light generated by extensive air showers (EASes).

Status of the SPHERE experiment

Here is presented the current state of the SPHERE-2 balloon-borne experiment. The detector is elevated up to 1 km above the snow surface and registers the reflected Vavilov-Cherenkov radiation from extensive air showers. This method has good sensitivity to the mass-composition of the primary cosmic rays due to its high resolution near the shower axis. The detector consists of a 1500 mm spherical mirror with a 109 PMT cluster in its focus. The electronics record a signal pulse profile in each PMT. In the last 2 years the detector was upgraded: time resolution of pulse registration was enhanced up to 12.5 ns, channel sensitivity was increased by a factor of 3, a new LED-based relative PMT calibration method was introduced, and new hardware and etc. was installed.

The SPHERE experiment: Baikal 2010

The SPHERE-2 detector was lifted above the snow-covered surface of Lake Baikal by a captive balloon several times in 2010. The Vavilov-Cherenkov radiation of extensive air showers was measured. Preliminary results from processing the data of the SPHERE-2 experiment at various altitudes of observation are presented.