Представлен новый метод оценки типа частиц первичных космических лучей в области энергий 10–1000 ПэВ для индивидуальных событий, зарегистрированных установкой СФЕРА-2. Метод основан на сравнении образов зарегистрированных событий с моделированными событиями в предположении различных типов первичной частицы с учетом погрешностей измерения. Исследование направлено на поиск предела чувствительности в определении химического состава первичных космических лучей сверхвысоких энергий при использовании метода регистрации отраженного черенковского света широких атмосферных ливней.

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).

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.

В начале 2010 г. проведено несколько подъемов установки СФЕРА-2 с помощью привязного аэростата над заснеженной поверхностью озера Байкал. Были проведены измерения черенковского света широких атмосферных ливней (ШАЛ). Приведены предварительные результаты обработки данных эксперимента СФЕРА-2 на различных высотах наблюдения.

Characteristics of air-shower-triggered atmospheric families detected in the hybrid experiments together with emulsion chamber and As-array at high mountains are compared with those of simulations. The analysis of families accompanied by air-showers with N(e) >= 10(7) shows that the experimental family-energy distribution favors a proton-dominant chemical composition of primary cosmic-rays but the lateral distribution favors a heavy-dominant composition. Thus no simulations can describe the overall characteristics of the data of hybrid experiments.

The Ne spectrum of extensive air showers at Ten-Shan (experiment HADRON) is analyzed. It is shown, that around 10(17) eV a bump is observed in the spectrum. A sharp break in the spectrum at 3 PeV and the bump at 100 PeV are interpreted as an additional CR component, caused by the radiation from one or two close CR sources. It is noticed, that the mass composition of the basic CR component and the additional one can differ.

The expedition carried out; in March, 2008 to Lake Baikal became an important stage in the development of the SPHERE experiment. During the expedition the SPHERE-2 installation was hoisted, for the first time, on a tethered balloon, APA, to a height of 700 to over the lake surface covered with ice and snow. A series of test measurements were made. Preliminary results of the data processing are presented. The next plan of the SPHERE experiment is to begin a set of statistics for constructing the CR spectrum in the energy range 10(16) - 10(18) eV.

At the last Symposium it was the view that the problem of the knee in the CR spectrum is practically solved and does not demand further experimental investigation. A frequent basis for this opinion is the simulation dependent procedure of extracting the information oil the CB. mass composition. This report is a survey of the experimental data which contradict such a point of view. These data point to the restricted self-descriptiveness of some EAS installations and show the shortcomings of some processing methods. Therefore, not looking to continue research for another 50 years, we present a solution to the problem of the knee.

Characteristics of the air-showertriggered atmospheric families detected in the hybrid experiment together with emulsion chamber and AS-array at Mt. Chacaltaya, Tibet and TienShan are studied in detail by comparing with those of CORSIKA simulations using interaction models of QGSJET, SIBYLL and EPOS. In the Chacaltaya data, family-energy distribution in the events with air-shower size of Ne ≥ 107 is favorable to heavy-dominant chemical composition of primary cosmic-rays but the lateral distribution is favorable to heavy-dominant composition. The Tien-Shan data, however, energy and lateral characteristics of the EAS-triggered families are not much different from those expected in simulations using QGSJET and EPOS models.

The combined (EAS+EC) «Hadron» experiment was made at Tien-Shan Station during 1985–1991. A large statistic of gamma-hadron families, combined with EAS, is now analysed. The result of the leader effect disappearance forN e>107 was reported earlier and at this Conference too. Here we present new results about the existence of Super Young Showers (SYS) with ageS<0.1, containing gamma-hadron families with visible energy ≥10 TeV. Namely, SYS have anomalous soft-energy spectra of particles at gamma-hadron families. These events may be connected with Young Air Showers (YAS) and Narrow Air Showers (NAS).