M.I. Panasyuk

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.

On the problem of lunar radiation environment

In connection with projects of manned bases on the Moon it becomes topical to estimate radiation danger for their inhabitants. In this paper we describe a method of evaluation of the radiation environment on the lunar surface produced by galactic and solar cosmic rays. The roles of both primary and secondary radiations generated in the depth of the lunar soil under the action of high-energy protons and nuclei are taken into account. Calculated fluxes of particles are used in order to estimate annual averaged absorbed and equivalent local dose rates in tissues. It is established that in the lunar rock the contribution of secondary neutrons to the dose rate exceeds that of protons. The contribution of the secondary particles generated by nuclei of galactic cosmic rays to the dose rate is estimated.

Estimation of radiation risk for astronauts on the Moon

The problem of estimating the risk of radiation for humans on the Moon is discussed, taking into account the probabilistic nature of occurrence of solar particle events. Calculations of the expected values of tissue-averaged equivalent dose rates, which are created by galactic and solar cosmic-ray particle fluxes on the lunar surface behind shielding, are made for different durations of lunar missions.

Equivalent dose during long-term interplanetary missions depending on solar activity level

The method is presented for calculating the equivalent dose inside interplanetary spacecraft. Use is made of the Russian-developed galactic cosmic ray and solar energetic particle models and SHIELD transport code. The contributions from different corpuscular radiation components to the total equivalent dose are examined as dependent on spacecraft shielding thickness. Quantitative estimates have been obtained for spacecraft on the Earth-Mars-Earth route during solar minimum and maximum.