核科学百年讲座第七讲核科学技术在材料科学中的应用

核科学技术和材料科学的结合产生了一门新兴的交叉学科——核材料(也称核固体)，主要指核技术在材料分析、物质改性和新材料研制合成中的应用．文章介绍核技术在材料科学中的应用历史、现状及其前景，包括基本物理原理．     

Magnetic monopoles — a brief review

Magnetic monopoles were first considered in detail by DIRAC in a 1931 paper, where he proved a charge-quantization theorem. The experimental searches which followed proved fruitless. Recently there has been a rapid increase in theoretical and experimental work in this field. A highly controversial detection claim was made by PRICE, SHIRK, OSBORNE and PINSKY in 1975. Report has also come of a possible monopole detection at Stanford university in February, 1982.     

Nuclear track radiography of “Hot” aerosol particles

Nuclear track radiography was applied to identify aerosol “hot” particles which contain elements of nuclear fuel and fallout after Chernobyl NPP accident. For the determination of the content of transuranium elements in radioactive aerosols the measurement of the -activity of “hot” particles by SSNTD was used in this work, as well as radiography of fission fragments formed as a result of the reactions (n,f) and (γ,f) in the irradiation of aerosol filters by thermal neutrons and high energy gamma quanta. The technique allowed the sizes and alpha-activity of “hot” particles to be determined without extracting them from the filter, as well as the determination of the uranium content and its enrichment by ²³⁵U, ²³⁹Pu and ²⁴¹Pu isotopes. Sensitivity of determination of alpha activity by fission method is 5×10⁻⁶ Bq per particle. The software for the system of image analysis was created. It ensured the identification of track clusters on an optical image of the SSNTD surface obtained through a video camera and the determination of size and activity of “hot” particles.     

Track detectors in radiation monitoring of the sunken submarine “Komsomolets”

Track method (using the CN and CR-39 detectors, spark couner of tracks as well as selective sorbents for plutonium and uranium) is applied in 1994 and 1995 together with many other methods in radioecological monitoring of water in the region of the sunken nuclear submarine (NS) “Komsomolets”. The detection assembles were installed with the help of the submersibles MIR. The results obtained inside the NS and on its surface as well as near and on the remote buoy station do not contradict the data obtained by other methods confirming the absence of the plutonium leakage outside of the submarine.     

Man-made plutonium in environment — possible serious hazard for living species

It is pointed out that, contrary to the situation with natural Rn, the growing concentration of man-made Pu in environment — natural water soil plants and food — can provide the serious danger for all kind of animals and especially for mankind. Really, as it was established recently, element Pu is accumulated in human body during all the life and the dangerous concentration estimated to be 10⁻¹² – 10⁻¹³ grapm Pu per gram of human tissues. Unfortunately up to now there are no simple nonexpensive methods of Pu determination at the level of sensitivity 10⁻¹⁴ – 10¹⁵ g/g which can provide the determination of Pu even in 0.2 g of human tissue. We warn that now the average concentration of Pu in human body is not less than 10⁻¹⁴ g/g and much higher for some “hot” regions in Europe and Asia. We propose to discuss the problem of organizing world net exploration of Pu in environment — similarly to Rn exploration program — and personnel Pu monitoring for inhibitions of Pu damaged regions. Our approach to the problem is based on chemical separation of Pu, on determination of Plutonium by high fission cross section with thermal neutrons ²³⁹Pu(n,f) reaction and by control of possible admixture of ²³⁵U isotope by ²³⁸U(γ, f) reaction in Pu preparations. The problem of increasing of sensitivity of Pu analysis up to 10⁻¹⁴ – 10⁻¹⁵ g/g is discussed in detail.     

Influence of intensive γ and electron radiation on tracks formation in the PM-355 detectors

Solid-state nuclear track detectors have found wide use in various domains of science and technology, e.g. in plasma experiments. The track detectors used in the fusion-oriented experiments encounter “harsh” conditions (intense X-ray and neutron radiation, heat impact, shock waves and plasma fluxes). Therefore, such detectors should be tested under similar conditions. This paper concerns influence of electron and γ radiation on the track formation in PM-355 detectors. Samples were irradiated with 1.5-MeV protons and ⁴He-ions, and with 5.5 MeV particles. After that they were exposed to γ and electron radiation. Irradiation doses were varied from 100 kGy up to 2000 kGy. The etching was performed in steps, and a bulk etching rate (V_B) was determined versus an absorbed dose of electron and gamma radiation.     

Calculations of track parameters and plots of track openings and wall profiles in CR39 detector

Computer programs have been developed to calculate track parameters and to plot track openings and wall profiles. The programs are based on equations derived for three-dimensional consideration of track development. All possible cases of track openings and wall profiles are obtainable from these equations. Results are given for lengths of major and minor axes, track depths and surface areas of track openings. Some examples of track openings and wall profiles are also presented.     

核科学百年讲座第四讲核 能与核电

文章主要介绍了核能的发展历史、物理机制、主要优点以及核电形式核能的利用．核电的主要优点以耐用、清洁、经济、安全为特点．文章还介绍了世界核能利用的历程、现状以及核能在我国的发展和利用．     

Proposal for a new class of ssntd's — magnetic bubble domain detectors

The mechanism of registration and dynamic characteristics of threshold detectors of the heavy charged particles are considered theoretically on the basis of magnetic integrated circuits on bubble magnetic domains.     

Annealing of 54 132 Xe-ion tracks in Lexan and Makrofol plastic track detectors

Samples of Lexan and Makrofol-E polycarbonate plastic track detectors were exposed to 1·1 MeV/N ₅₄ ¹³² Xe-ions to investigate the thermal track fading properties of these plastics. The experimental results show that there is no effect of annealing on the bulk etch rate while the track etch rate decreases with annealing. The track diameter decreases with increase in annealing time and temperature. It is also observed that the track density is reduced as a result of annealing. The experiments reveal that the track lengths are, in general, decreased by the application of heat and that the oblique tracks are less stable than the vertical tracks. The decrease in diameter of ₅₄ ¹³² Xe-ion tracks in Makrofol-E due to heat treatment is faster than that of ₅₄ ¹³² Xe-ion tracks in Lexan.     

Discrete breathers — Advances in theory and applications

Nonlinear classical Hamiltonian lattices exhibit generic solutions — discrete breathers. They are time-periodic and (typically exponentially) localized in space. The lattices have discrete translational symmetry. Discrete breathers are not confined to certain lattice dimensions. We will introduce the concept of these localized excitations and review their basic properties including dynamical and structural stability. We then focus on advances in the theory of discrete breathers in three directions — scattering of waves by these excitations, persistence of discrete breathers in long transient processes and thermal equilibrium, and their quantization. The second part of this review is devoted to a detailed discussion of recent experimental observations and studies of discrete breathers, including theoretical modelling of these experimental situations on the basis of the general theory of discrete breathers. In particular we will focus on their detection in Josephson junction networks, arrays of coupled nonlinear optical waveguides, Bose–Einstein condensates loaded on optical lattices, antiferromagnetic layered structures, PtCl based single crystals and driven micromechanical cantilever arrays.     

Doped nanocrystalline materials — Physics and applications

The properties and applications of nanocrystals doped with transition and rare-earth impurities are reviewed. The high efficiency and ultrafast recombination times observed in these doped nanocrystals make these materials very attractive for optoelectronic applications.     

Measurement of target fragments produced by 160 MeV proton beam in aluminum and polyethylene with CR-39 plastic nuclear track detectors

Production of target fragments from reactions of 160 MeV proton beams in aluminum and polyethylene was measured with CR-39 plastic nuclear track detectors (PNTD). Due to the detection limit of PNTD, primary protons cannot be detected; only low-energy short-range target fragments are registered. As a feasibility study, a so called “two step etching method” was employed to get the linear energy transfer (LET) spectra, absorbed dose, and dose equivalent. This method is discussed in this paper, together with the measured results.     

Light propagation analysis in graded index fiber—review and applications

The quadratic graded index (GRIN) is a fiber that gives physical interpretation of the recently introduced mathematical operation coined the fractional Fourier transform (FRT). This paper reviews the FRT, GRIN, and their relations. Possible applications are demonstrated. In particular the Talbot effect inside the GRIN is analyzed.     

Fibre-optic systems for dynamic light scattering — a review

‘Photon correlation spectroscopy’ has become a standard method in applied science for analysing the properties of submicron particles in a fluid environment. The fast, local fluctuations in the intensity of the light scattered from such particles are recorded and analysed in terms of the local motions. This has led to the use of the method both to characterize particle geometry and to monitor particle translation as a marker for fluid flow. The advent of fibre-optics has enabled portable, small, remote and more flexible systems to be established in recent years. This paper reviews those instrument designs which have represented advances in the development of fibre-based systems. Emphasis is laid on instruments (a) for monitoring blood flow and (b) for measuring Brownian-induced translatory diffusion in colloidal suspensions.     

Science and technology with nuclear tracks in solids

Fission track dating has greatly expanded its usefulness to geology over the last 40 years. It is central to thermochronology—the use of shortened fission tracks to decipher the thermal history, movement, and provenance of rocks. When combined with other indicators, such as zircon color and (U–Th)/He, a range of temperatures from C to C can be studied. Combining fission track analysis with cosmogenic nuclide decay rates, one can study landscape development and denudation of passive margins. Technological applications have expanded from biological filters, radon mapping, and dosimetry to the use of ion track microtechnology in microlithography, micromachining by ion track etching, microscopic field emission tips, magnetic nanowires as magnetoresistive sensors, microfluidic devices, physiology of ion channels in single cells, and so on. In nuclear and particle physics, relatively insensitive glass detectors have been almost single-handedly responsible for our knowledge of cluster radioactivity, and plastic track detectors together with automated measuring systems have been used at the Bevalac, Brookhaven, CERN, and GSI, mainly to study fragmentation of high-energy heavy nuclei. Almost everything we know about the ultraheavy cosmic rays has been learned using Lexan on the Long Duration Exposure Facility and BP-1 phosphate glass on the Mir Station. New topics include development of calorimetric aerogels capable of measuring kinetic energies of hypervelocity interstellar and interplanetary dust grains in space and research on identification of strains of Bacillus spores by measurements of their size and swelling rates when humidified.     

核科学百年讲座第一讲 历史性发现及其对人类社会的影响(Ⅰ)

第一讲和第二讲系统地介绍了核科学发展历史，特别是核科学中的历史性发现和重大应用．主要综述核科学的早期发展历史，总体介绍核科学中最基本的重大发现，如放射性、电子、质子、中子、原子核裂变和衰变的发现．介绍人类认识原子和原子核的历史过程，包括与之相关的著名实验和理论．通过介绍核科学的发展和应用，展示了核科学技术对自然科学本身及其对人类社会的深远影响和巨大贡献．     

Determination of spatial and energy distributions of neutrons in experiments on transmutation of radioactive waste using relativistic protons

The experiments on transmutation of ¹²⁹I and ²³⁷Np using uranium-lead targets surrounded by a paraffin moderator were performed at the Joint Institute for Nuclear Research (JINR, Russia). The targets were irradiated by 1.5 GeV and 7.4 GeV protons at the Synchrophasotron of JINR. In the frame of present work spatial and energy distributions of neutrons on the surface of the paraffin moderator were measured using SSNTD technique. It is shown that measured values of spetral indices do not pretend on the energy of incident protons but depend on the target composition. The presence of the uranium insertion softens neutron spectra.     

Fissile radionuclides in thyroid of the inhabitants of the gomel region in belarus and peculiarities of their distribution

Severe radiation damages with the following substitution of connective tissue are the effect of high doses in microvolumes of the thyroid. Calcium, strontium and uranium deposited into these sections was more as compared to a normal tissue of the thyroid. An estimation of the microdistribution of fissile radionuclides was carried out using the method of fragmental radiography. The analysis of tracks done visually using a microscope magnification of 300 revealed the local density of fission fragments up to 10³ mm⁻². The irradiation of the surrounded cells which contain the hidden genetic damages, initiated by radioiodine, does not exclude their possible promoter role in thyroid cancerogenesis.