Proton-Induced Gamma Ray and Neutron Emissions
Study of the Characteristics of High-Energy Proton-Induced Gamma Ray and Neutron Emissions from Materials that Imitate Surfaces of Planets
Tech Area / Field
- PHY-ANU/Atomic and Nuclear Physics/Physics
3 Approved without Funding
ITEF (ITEP), Russia, Moscow
- Centre d’Etude Spatiale des Rayonnements, France, Toulouse\nUniversity of New Mexico / Institute of Meteoritics, USA, NM, Albuquerque\nUniversity of Arizona / Department of Planetary Science, USA, AZ, Tucson\nWaseda University / Advanced Research Institute for Science and Engineering, Japan, Tokyo\nNational Institute of Radiological Science, Japan, Chiba
Project summaryThe proposal is aimed at experiments to determine the space-energy characteristics of the neutron and gamma ray emission fields generated by 0.2-0.8 GeV proton irradiation of thick targets composed of various elements.
At present, the data on the physical properties of secondary radiations from substances and materials irradiated by intermediate- and high-energy protons are lacking when making some fundamental and applied researches in astrophysics, in space physics, in atomic and nuclear physics, as well as when designing and operating the latest accelerators.
The said researches include
- determination of the elemental composition of planetary surfaces monitored by the satellites capable of recording neutrons and g-rays (orbital spectrometry);
- designing radiation shielding for charged particle accelerators;
- verification and validation of the model parameters for high-energy hadron -nucleus interactions bearing on the researches.
Orbital spectrometry determines the chemical abundances of planetary surfaces with little or no atmosphere and provides valuable clues to the origin and evolution of planets.
The g-ray and neutron production in nuclear interaction of high-energy protons with matter may be simulated using proton accelerators.
It should be borne in mind that the perse physical and technological conditions and tasks that may arise when studying the various aspects of the above researches necessitate extensive usage of the latest simulation codes based on the present-day model representations of hadron-nucleus interactions in the above-mentioned range of projectile proton energies.
However, the present-day accuracy and reliability of the calculation data obtained with the simulation codes are insufficient for any unambiguous physical conclusions to be drawn from solving both fundamental and applied problems. Therefore, benchmark experimental data must be accumulated with a view to perfecting the physical models and modifying the simulation codes. In this connection, the benchmark data acquisition becomes an urgent task of the proton beam experiments.
In designing and making the proton beam experiments, the volumes of the studied materials have often to be comparable with the effective planetary depths involved in production of the backward gamma and neutron emissions, as well as with the shielding thicknesses of charged-particle accelerators. Should this condition be disregarded, we have also to use some very uncertain model representations of the actual processes. Another important requirement is that the media, wherein protons interact with matter, should be selected to study. The media must correspond to the characteristic types of the planetary surface basic rocks (granites, basalts) and their constituent elements (aluminum, iron) and to the biological shielding materials (concrete, iron) of high-current accelerators.
The said conditions are determinant when designing the experiments to suit the above-formulated tasks. The experiments must essentially be aimed at studying the space-energy characteristics of the secondary radiation fields produced by interactions of the intermediate- and high-energy protons with great volumes of the above-mentioned materials. However, designing and realizing the experiments are very difficult, so they have not yet been made to the extent necessary for the tasks to be fulfilled. This relates particularly to the planetary surface materials.
The potentialities of the ITEP accelerator facility permits full-scale preparation and realization of the experiments in question. Attention will be paid mainly to
- measurements of the space-energy spectra of secondary g-quanta produced in the bulk targets made of the above-mentioned materials irradiated by protons of the energies characteristic of primary cosmic rays;
- study of space-energy distributions of secondary neutrons by measuring of threshold reaction rates under the above-mentioned conditions using activation detectors.
The experimental results are proposed to simulate by the computational codes used worldwide to calculate the high-energy hadron-nucleus and nucleus-nucleus interactions. The set of the codes includes LAHET (LANL), CASCADE (ITEP), GEANT (CERN), and, probably, some others.
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