V.P. Pavlyuchenko

A new method of ionization-neutron calorimeter for direct investigation of high-energy electrons and primary nuclei of cosmic-rays up to the “knee” region

Abstract A new technique of the Ionization Neutron Calorimeter (INCA) to be installed aboard a satellite or a space station is capable of opening new horizons for cosmic-ray physics. The main goal of the experiment proposed is studying local nearby sources of high-energy cosmic rays by measuring the spectrum and composition of the nuclear component with the energy resolution of better than 30% that is sufficient for solution of these problems in the energy range 0.1–10 PeV, i.e., in the so-called “knee” region, and the spectrum of primary electrons in the energy range 0.1–10 TeV with the proton-background suppression factor up to 107. In addition, this experiment can provide new information on the cosmic-ray gamma-radiation in the energy interval 30 GeV–1 TeV, neutrons and gamma-rays from solar flares, and the existence of very massive exotic charged particles in cosmic radiation. The INCA is a calorimeter combining properties of conventional ionization calorimeters and classical neutron monitors. It can measure both the ionization produced by charged particles and evaporation neutrons arising as a result of excitation of heavy-absorber nuclei by cascade particles. The advantages of the INCA are not only excellent electron–proton separation but a high geometry factor of about 2 m 2 sr / ton owing to the INCA optimized composition and shape, whereas conventional ionization calorimeters are usually limited by geometry factor on the order of 0.1 m 2 sr / ton . To verify the INCA concept, a prototype was constructed and exposed to pion and proton accelerator beams with energies of 4 and 70 GeV, respectively, and to an electron beam with an energy of 200–550 MeV. The experimental data obtained agree well with the results of a Monte Carlo simulation by the SHIELD code.

The modern conception of the INCA project

Abstract The goals and status of the INCA Project are presented. New technique based on the ionization-neutron calorimeter (INCA) and designed to study the energy spectrum and composition of the primary cosmic radiation in the “knee” region as well as the spectrum of primary electrons in the range 0.1–10 TeV is discussed.

The first results obtained with the installation HORIZON-T

A new installation HORIZON-T is commissioned at the high altitude scientific station of P.N. Lebedev Institute at the Tien-Shan Mountains. The purpose of this installation is to study EAS arriving at the zenith angles close to the horizon. The installation consists of three Vavilov – Cherenkov detectors located at the center of the installation and five registration points for muons which are placed within 500 m from the center. With the help of HORIZON-T installation EAS events have been detected at zenith angles more than 65 degrees, some of which had muon pulses with the front being ahead of one from Vavilov – Cherenkov pulses by more than 20 ns. Simulations show that such EAS are most likely initiated by primary nuclei with the mass more than 10.

PCR nuclear composition at 1–30 PeV according to lateral distributions of electrons in EAS accompanied by high energy particles in emulsion chambers

New data on the primary cosmic ray nuclear composition were derived from the electron lateral distributions of EAS at Tien-Shan. The dependence on EAS electron size is presented from Ne = 5·105 to 3·107. Data were obtained for all EAS as well as for EAS accompanied by high energy gamma-rays and hadrons in X-ray emulsion chambers. According to model simulations the latter events are generated predominantly by primary protons. Results showed that the fraction of protons and light nuclei does not decrease above the “knee” from Ne = 106 up to 107 (∼10 – 20 PeV primary energy).

The INCA project: present status and outlook

Abstract Scientific objectives, foundations, status, and outlook of the INCA Project are presented. Fundamentally new technique based on the ionization-neutron calorimeter (INCA) and designed to study local nearby sources of high-energy cosmic rays by direct measuring the spectrum and composition of the nuclear component in the “knee” region and the spectrum of primary electrons in the energy range 0.1–10 TeV with the proton-background suppression factor up to 107 is discussed. Experimental data on exposition of the INCA prototypes to electron, pion, and proton beams at various energies and corresponding simulation results are presented. Prospects are considered.