Radiation Damage In Solids Research Articles

The Essence and Application of the Optical Absorption Method for Quantitative and Qualitative Analysis of Radiation Defects in Optical Crystals

Today ionic crystals are widely used in devices for various purposes. In X-ray spectral optics they are widely used as crystal monochromators; ionic crystals are used in optical devices where lenses and transparent optical media (light filters) are made of optically pure materials - ionic crystals. In general, the main positive feature of these materials is transparency regarding the transmission of radiation in the visible region of the spectrum (transmittance of about 0.9) and neutrality - that is, approximately the same reaction of the medium to different spectral ranges of radiation. Ionic crystals are also widely used in detectors (scintillators, ionizing radiation dosimeters) and lasers. They are also widely used in acousto-optics and electrical engineering (lines of electrical signals delay, which gain efficiency due to the relatively small absorption of ultrasonic waves, and, therefore, it is possible to work with a wide sequence of signals probing the crystal). It is known that when ionizing radiation passes through ionic crystals, color centers appear in them, which can change the spectral composition of radiation both in the UV region and in the visible range. For example, the simplest configurations of color centers (F-centers) lead to the appearance in optical materials of additional absorption bands localized on the wavelength axis with a maximum at the wavelength lmax = 248 нм , but more complex configurations of radiation damage in solids already lead to the appearance of absorption bands at wavelengths in the visible range. This already presents some difficulties for developers and designers of relevant equipment, as changes in the spectral composition of radiation passing through the optical system of the device can lead, for example, to loss of efficiency of the selected radiation receiver, the main characteristic of which is primarily spectral sensitivity. Taking into account possible changes in the spectral composition of radiation is an important and urgent task of modern optical instrumentation. The purpose of this work is the analysis and justification of a method that takes into account structural changes in externally irradiated ionic crystals.

Deterministic Role of Collision Cascade Density in Radiation Defect Dynamics in Si.

The formation of stable radiation damage in solids often proceeds via complex dynamic annealing (DA) processes, involving point defect migration and interaction. The dependence of DA on irradiation conditions remains poorly understood even for Si. Here, we use a pulsed ion beam method to study defect interaction dynamics in Si bombarded in the temperature range from ∼-30 °C to 210 °C with ions in a wide range of masses, from Ne to Xe, creating collision cascades with different densities. We demonstrate that the complexity of the influence of irradiation conditions on defect dynamics can be reduced to a deterministic effect of a single parameter, the average cascade density, calculated by taking into account the fractal nature of collision cascades. For each ion species, the DA rate exhibits two well-defined Arrhenius regions where different DA mechanisms dominate. These two regions intersect at a critical temperature, which depends linearly on the cascade density. The low-temperature DA regime is characterized by an activation energy of ∼0.1 eV, independent of the cascade density. The high-temperature regime, however, exhibits a change in the dominant DA process for cascade densities above ∼0.04 at.%, evidenced by an increase in the activation energy. These results clearly demonstrate a crucial role of the collision cascade density and can be used to predict radiation defect dynamics in Si.

Radiation defect dynamics studied by pulsed ion beams

The formation of stable radiation damage in solids often proceeds via complex dynamic annealing processes, involving migration and interaction of ballistically-generated point defects. Our current understanding of the underlying physics is still not sufficient for predicting radiation damage even for Si, which is arguably the simplest and most extensively studied material. The complexity of radiation damage is closely related to radiation defect dynamics. Here, we demonstrate how defect interaction dynamics can be studied by pulsed beam irradiation when the total ion fluence is split into a train of equal square pulses. By varying the passive portion of the beam duty cycle, we measure a characteristic time constant of dynamic annealing and, hence, the defect relaxation rate. Measurements of stable lattice disorder as a function of the active portion of the beam duty cycle give an effective defect diffusion length. We illustrate the pulsed beam method with examples for Si bombarded at 100°C with 500keV Ar ions.

Mechanisms and kinetics of nuclear track etching and annealing: Free energy analysis of damage in fission fragment tracks

Mechanisms and kinetics of etching and annealing of fission fragment tracks in CR-39 have been investigated. Kinetics of bulk etching and that of fission fragment track etching in CR-39 are described in a systematic manner. Activation energies of etching and annealing were determined from the experimental results through Arrhenius type, t=toexp(Ea/kBT), empirical relationships and models. The increase of free energy in fission fragment track formation in CR-39 is also determined from the measurements of track parameters. Activation barriers of bulk etching, track etching and track annealing in CR-39 are compared and discussed. This paper presents an anatomy of fission fragment tracks. Analyses of experimental results and comparison of above mentioned energies have yielded the important physics information usable in nuclear track methodologies, including nuclear geophysics and geochemistry, and radiation damage in solids.

Displacement cascade decomposition within the Binary Collision Approximation

ABSTRACTThe mechanism of damage production in solids during irradiation is of great practical interest in nuclear technology. The need to increase the life time of current nuclear plants as well as extreme conditions (high temperature and high neutron flux) in new generations of nuclear plants leads to have a deep insight into radiation damage in solids. In fact, the slowing down of particles in solids leads to a non homogeneous distribution of defects in solids, giving rise to complex microstructures with unusual properties. Numerous experiments, Molecular Dynamics (MD) and Monte Carlo (MC) simulations have clearly shown that highly damaged areas called displacement cascades are produced by neutron or impinging ions in solids. It is now clearly established that the number and the distribution of these subcascades dictate the long term evolution of the microstructure under irradiation. In this work, we present a new model to calculate the mean number of displacement cascades produced in a mono-atomic solid by an incident particle within the Binary Collision Approximation framework (BCA) taking into account all information extracted from MD simulations. To reach such a goal, the notion of subcascade threshold energy is introduced and discussed on some examples. Within this formalism, we exhibit a new way to estimate the number of defects created in a displacement cascade integrating results of MD simulations of cascades.

A framework for understanding fast-neutron induced defects in SiO2 MOS structures

Neutron radiation damage in solids results from nuclear collisions and reactions that produce energetic recoil atoms. The recoiling atoms slow down in the host material through nuclear and electronic collisions. During a nuclear collision, energy is transferred to translatory motion of another atom, whereas during an electronic collision, energy is transferred to atomic electrons, leading to electronic excitation or ionization. Nuclear collisions may result in displacing additional host atoms from their lattice sites if the energy received by the host atom is greater than the displacement threshold energy. As neutrons pass through the thin thermally grown gate oxide of a MOSFET device, they produce both silicon and oxygen primary knock-on atoms (PKAs). These PKAs can produce significant displacement damage regions in the bulk oxide which become potential hole traps or mobile ionic charge traps similar to the condition at the SiO2/Si interface. It is also suspected that these PKAs may deposit part of their energies into plasmons, which will eventually decay to electron-hole pairs causing charge buildup at the interface, when the MOSFET device is in operation. Since the gate oxide region is susceptible to electronic effects, it is important to know the amount of damage from individual neutron interactions in the oxide layer. A key to a theoretical study is provided in this paper. Analytical and direct-simulation estimates are made of the neutron damage.

Radiation Damage in Solids Studied by <sup>119</sup>Sn Mössbauer Effect Spectroscopy

Radiation Damage in Solids Studied by <sup>119</sup>Sn Mössbauer Effect Spectroscopy

Radiation damage in crystalline and amorphous dielectrics

Abstract Radiation induced processes in crystalline and amorphous solids are discussed. The primary act of ionizing radiation is similar in both materials. The majority of secondary radiation stimulated processes in crystalline and amorphous solids are similar, too. Differences may occur in focusing collisions and channelling processes where the interaction takes place in the host lattice. Besides, the present paper is concerned with the study of recent developments in radiation damage in solids (radiation colloids, swelling effects).

Authors

Authors

Simulation of Radiation Damage in Solids

A combined theoretical and experimental study of primary recoil spectra effects or radiation damage in silicon is presented. Calculations determined how the damage energy is partitioned into free defects and cascades by fast collisions. The theory also showed that on a time scale ~10-14 sec. a very weak mass dependence of the lattice damage is to be expected. Channeling experiments were then performed on <111> single crystal silicon implanted with 1.0 MeV 20Ne, 0.5 MeV 4He and 75 keV 1H. Energies and fluences of the ions were matched such that over the first 0.3μm the damage energy deposited and the rate of energy deposition were the same for all species. The experimental data were analyzed assuming that equivalent primary damage states will evolve into statistically equivalent final damage states at high fluences. They confirm that the final damage is essentially independent of the mass of the bombarding ion.

Photocounting distributions for exponentially decaying sources

Exact photocounting distributions are obtained for a pulse of light whose intensity is exponentially decaying in time, when the underlying photon statistics are Poisson. It is assumed that the starting time for the sampling interval (which is of arbitrary duration) is uniformly distributed. The probability of registering n counts in the fixed time T is given in terms of the incomplete gamma function for n >/= 1 and in terms of the exponential integral for n = 0. Simple closed-form expressions are obtained for the count mean and variance. The results are expected to be of interest in certain studies involving spontaneous emission, radiation damage in solids, and nuclear counting. They will also be useful in neurobiology and psychophysics, since habituation and sensitization processes may sometimes be characterized by the same stochastic model.

On two cascade models

Two cascade models are presented which have quite analogous mathematical formulation. The first one is the statistical model of radiation damage in solids and the second is the random space filling or parking problem.

1116. Investigation of spectrum of optical radiation at bombardment of silicon: V I Bendikov et al,Radiation damage in solids, coll, vol 1, Kiev 1974, 24–25 ( in Russian)

1116. Investigation of spectrum of optical radiation at bombardment of silicon: V I Bendikov et al,Radiation damage in solids, coll, vol 1, Kiev 1974, 24–25 ( in Russian)

1114. Proton microscopy investigation of kinetics of damage and annealing of silicon and germanium single crystals in conditions of ion bombardment: V G Zlobin et al,Radiation damage in solids, coll, vol 1, Kiev 1974, 21–22 ( in Russian)

1114. Proton microscopy investigation of kinetics of damage and annealing of silicon and germanium single crystals in conditions of ion bombardment: V G Zlobin et al,Radiation damage in solids, coll, vol 1, Kiev 1974, 21–22 ( in Russian)

BOOK AND FILM REVIEWS: Film Review: The Damage Is Done: Radiation Damage in Solids

BOOK AND FILM REVIEWS: Film Review: The Damage Is Done: Radiation Damage in Solids

Diffusion-Controlled Reaction Kinetics

The theory of diffusion-controlled correlated reaction kinetics is developed for the radiation boundary condition (RBC) at the reaction surface. Limited only by the assumptions of purely radial spatial dependence, of a spherical reaction surface, and of continuum diffusion, these results comprise a complete solution for these kinetics. The limiting solutions are obtained for the case of the Smoluchowski boundary condition (SBC) at the reaction surface; numerical solutions are presented, as are the analytic forms of certain limiting cases. The initial recovery for the RBC is linear in time, whereas for the SBC it is well known to be proportional to the square root of time. The discussion is presented in the context of radiation damage in solids, although the results are applicable to other fast-kinetics systems, e.g., radiation and photophysics, chemistry, and biology.

Time-Dependent Relaxation of Aligned Nuclei due to Radiation-Induced Vacancies in Solid Germanium

We observe the temperature dependence of the alignment of an isomeric state in $^{73}\mathrm{As}$ (426 keV, ${\frac{9}{2}}^{+}$, $\ensuremath{\tau}=8 \ensuremath{\mu}sec$), produced by the reaction $^{72}\mathrm{Ge}(d,n)^{73}\mathrm{As}$ in solid Ge. The relaxation process can be interpreted with a diffusion-controlled time-dependent quadrupole interaction due to radiation-induced lattice damage. A diffusion energy of $E=1.3\ifmmode\pm\else\textpm\fi{}0.2$ eV is assigned to the activation energy for excess vacancy diffusion. This result yields, for the first time, quantitative insight into relaxation mechanisms associated with radiation damage in solids, which may occur when implantation techniques and nuclear reactions are employed.

Chemical Effects of Nuclear Transformations

"Chemical Effects of Nuclear Transformations." Nuclear Science and Engineering, 25(3), pp. 308–309 Additional informationNotes on contributorsA. G. MaddockAbout the Reviewer: Alfred Gavin Maddock, Reader in Radiochemistry at Cambridge University and Fellow of St. Catharine3s College, graduated at Imperial College, London, where his research was supervised by H. J. Emeleus. Sometime after completing his thesis, he was attached to the British equivalent of the Manhattan Project. After nearly four years in Canada, and participation in the founding of the Chalk River and, later, the Harwell laboratories, he returned to Cambridge University. His principal research interests revolve around the chemical effects of nuclear transformation, radiation damage in solids, and the chemistry of the heavy elements, especially protactinium.

Step annealing in radiation damage in solids

Step annealing in radiation damage in solids

Radiation damage in body-centred metals: M W Thompson,Radiation Damage in Solids, Academic Press, 1962, 753–762

Radiation damage in body-centred metals: M W Thompson,Radiation Damage in Solids, Academic Press, 1962, 753–762