Investigation of latent and short etched heavy ion tracks in solids

In the past five years were carried out SANS (Small-Angle Neutron Scattering measurements in the JINR to investigate latent and short etched tracks in SSNTD. The results demonstrate the suitability of the method to study not etched and short etched tracks to analyse the etching process, e.g. for nuclear track filter production. The results are in good agreement with other methods as conductivity measurements.     

Energy loss dependent transversal etching rates of heavy ion tracks in plastic

By the method of electrolytical etching track etching rates V_t and corresponding transversal track etching rates V_trans of single heavy ion tracks in thin Makrofol KG foils have been measured at ion energies from 10–480 MeV/u. Makrofol KG foils of 8 μm thickness were irradiated perpendicular to the surface with ⁷⁹Au and ⁵⁴Xe ions at specific energies with energy loss values of REL=(10–90) ^*10³ MeVcm²/g at GSI Darmstadt, Germany, and Lawrence Berkeley Lab., Cal., USA. Using the electrolytical etching method by measuring the resistance of the foil during the etching process (etching conditions: 6n NaOH, room temperature and controlled 50° C) the breakthrough time and track etching rates V_t, V_trans and V_m (bulk etching rate) were analysed. Response curves (V_t/V_m)-1 as a function of Restricted Energy Loss (REL), the maximum extension of the ion induced damage perpendicular to the ion path and the dimension of the ion track core depending on the deposited energy can be estimated.     

High energy heavy ion tracks in bubble detectors

Bubble detectors which are commonly used as neutron detectors have been demonstrated through this study to be good detectors for registration of high energy heavy ion tracks. Large size bubble detectors made in China Institute of Atomic Energy were irradiated to heavy ions Ar and C up to 650 MeV/u and 400 MeV/u, respectively. Very clear features of stringy tracks of high energy heavy ions and their fragmentations are manifested and distinguishable. A single track created by a specific high energy heavy ion is composed of a line of bubbles, which is visible by naked eyes and retained for months wihhout reduction in size. The creation of heavy ion tracks in bubble detectors is governed by a threshold whose essence is approximately a critical value of energy loss rate (dE/dX)_c similar to that of etch track detectors. Ranges of heavy ions in bubble detectors are apparent and predictable by existing formulas. Identification of high energy heavy ions and the applications to heavy ion physics, cosmic rays, exotic particles and cancer therapy monitoring are obviously promising. The experimental and theoretical aspects of high energy heavy ion tracks in bubble detectors as well as the expectable applications are presented and discussed.     

Funnel-type etched ion tracks in polymers

It is shown that conical track etching is a much more complicated process than generally assumed. The choice of the corresponding parameters (i.e. the ratios of concentrations and diffusion coefficients of both etchant (e.g. NaOH) and stopping solutions (e.g. HCl) and the etching temperature) determines the ratio of polymer dissolution to etchant penetration. The latter value controls the counterplay of diffusion, etching, ionic conductivity, field emission and capacitive effects, which is decisive for both the final track shapes and their electronic properties. The stages of track evolution during etching under different conditions are outlined in detail. Both transparent conical nanopores and “funnel-type” tracks can be obtained, the latter consisting of a shorter cone and a residual latent track. Depending on the internal structure of that latent track segment, such funnel-type tracks either allow smooth transmission of the rectified currents or they emit unipolar current spikes. Not only the study of electronic properties of single ion tracks, but also of a multitude of tracks makes sense. Depending on the applied parameters, the individual track properties may either just add up, or new effects may be found that emerge from the interaction of the tracks among each other. This is preferentially the case for spike-emitting tracks, where effects such as phase-locked spike synchronization can be found as described by neural network theory.     

25 MeV/u Kr辐照下PET薄膜的损伤机制研究

通过25 MeV/u 86 Kr离子辐照叠层结晶聚对苯二甲酸乙二醇酯膜（PET）, 在不同的电子能损（3.40-7.25 keV/nm）和离子注量(5×1011----3×1012 ions/cm2)辐照条件下, 对Kr离子在PET中引起的辐照损伤效应进行了研究。借助傅里叶变换红外光谱分析,通过对样品的红外吸收峰进行扣除基底后的Lorentz拟合,分析了与主要官能团对应的吸收峰强度的变化趋势, 研究了化学结构与组分在重离子辐照下的变化规律; 利用X射线衍射光谱仪测量, 研究了Kr离子在PET潜径迹中引起的非晶化过程,并通过对吸光度和非晶化强度随离子注量的指数衰减规律的分析, 获得了不同电子能损离子辐照PET时主要官能团的损伤截面和非晶化截面及对应的潜径迹半径。 At room temperature, polyethylene terephthalate(PET) foil stacks were irradiated by 25 MeV/u Kr ions in the electronic stopping power range(3.3--7.66 keV/nm) and the fluence range from 5×1011 to 3×1012 ions/cm2. The behaviour of the main function groups with fluence and electronic stopping power were studied by using Fourier transform infrared(FTIR) spectroscopy, the degradation of the function group was investigated with the Lorentz fitting subtracted baseline. The amorphous processes in the latent tracks of PET were studied by X ray diffraction(XRD) measurements. The Kr ion induced degradation cross section and amorphisation cross sections(radii) for different electronic energy loss were acquired from the experimental data(FT IR and XRD) by exponential decay function respectively.      

Study of 18 40 Ar ion tracks in cellulose nitrate

Sample of cellulose nitrate (Russian) is exposed to ₁₈ ⁴⁰ Ar ions. The bulk etch rate has been studied at different etching temperatures and the activation energy for bulk etch rate has been calculated. The etched track lengths are measured for different etching times. The energy loss rate and range of ₁₈ ⁴⁰ Ar ions in CN(R) is also calculated. The critical threshold value for etchable track in CN(R) is determined by comparing the theoretical and experimental values of track length. The response curve of CN(R) is also presented.     

Heavy-ion particle spectrometry by track pattern in muscovite detectors

Muscovite mica detectors were irradiated with the ions: ¹⁹F of 47.5 MeV, ²⁴Mg of 57 MeV, ²⁸Si of 28 and 74 MeV, ³²S of 32 and 74 MeV, ⁶³Cu of 78.75 MeV and with neutron induced uranium fission fragments. Using optical microscopy, after an appropriate chemical etching, two characteristic etched track structure patterns were observed: a rhombic pyramid terrace structure for the Mg, Si and S ions, and a rhombic prism structure for the Cu ions and fission fragments. The use of these etched track patterns to discriminate two groups of ions between them, for the energy range covered in this work, is proposed.     

Track shapes,etching characteristics and track density distribution on different planes of apatite

Abstract

Studies concerning track shapes, etching characteristics and track density due to spontaneous fission of uranium along various crystallographic planes of apatite are represented. The studies were carried out on large complete crystals as well as on small grains of apatite belonging to various geological origins. Three track types (hexagonal, pyramidal and needle type) have been identified along various crystallographic planes.     

Qualitative analysis of ion tracks in Makrofol E

The track radius calculation reported by Tombrello was applied to experimental data of tracks from several ions and energies in Makrofol E. Qualitative analysis of ion tracks in this material is discussed. These data were also compared with values calculated using the Continuum Distorted Wave-Eikonal Initial State approximation     

Damage track detectors in radioprotection dosimetry: a novel approach

Limited sensitivity and unpredictable background are the major drawbacks of damage track detectors in the assessment of low neutron doses and low concentrations of alpha emitters in biological and environmental samples. The simplest way to increase the sensitivity of the damage track detectors is to increase both the exposure time and the detector area. However, the strong variability of the background may make this task often impossible. This background problem has been finally solved by a new registration method based on counting coincidence spots in geometrically matched pair of detectors. By using spark counting and electrochemical etching, both of which produce spots visible at low magnification, coincidences induced in two matched detector-surfaces by a few-microns-long tracks can be easily seen. This novel counting approach can be considered just the converse of those used in the past with Bi-fission detectors and cosmic ray stacks.     

Observations on the geometries of etched fission and alpha-recoil tracks with reference to models of track revelation in minerals

The kinetic and atomistic theories of crystal growth and dissolution are used to interpret the shapes and orientations of fission-track, recoil-track and dislocation etch pits in tri-octahedral phlogopite and di-octahedral muscovite. An atomistic approach combined with symmetry considerations lead to the identification of the periodic bond chains that determine the etch pit morphologies and relative etch rates at a chemical level: O–Mg–O in phlogopite, O–Mg–O–Fe in biotite and O–Al–O in muscovite. Using first-order estimates of the bond strengths, it is possible to account for the relative track etch rates in these minerals. The reported, sometimes simultaneous, occurrence of triangular, polygonal and hexagonal etch pit contours in phlogopite, some of which violate the crystal symmetry, suggests that the cohesion of the phlogopite lattice is lost over a much larger radius than that of the track core around the trajectories of particles for which the energy loss exceeds a threshold value. This is interpreted as an indication of pronounced sublattice and anisotropic effects during track registration.     

Detection efficiency of fission tracks in apatite related to mica external detectors by the spike irradiation technique

Detection efficiency of fission tracks in non-annealed and annealed Durango apatite crystals related to mica external detectors for fission track dating was estimated experimentally using the spike irradiation technique [Suzuki, 2002a. Abstracts of 21st International Conference on Nuclear Tracks in Solids, p. 22]. The relation of the fission track density between apatite samples and mica external detectors is an important parameter for the determination of fission track ages using an absolute approach especially for crystalline minerals. Spike irradiation of uranium-235-induced fission fragments was carried out using a high uranium content glass, GE1497, fixed firmly on the sample surface. Experimental works were carried out for sections parallel and perpendicular to the crystallographic c-axis of apatite. The detection efficiency of fission tracks in non-annealed apatite related to the mica external detectors was estimated to be 0.90 for the prism face and 0.99 for the basal face. The fission track age of Durango apatite averaged for the prism and basal faces was estimated to be 30.6 (±2.5) Ma, which is concordant with reference values reported previously, using the detection efficiency data with a B₀ value of the CN5 monitor glass and a U-238 spontaneous decay constant value of . The results also indicate that the B₀ age calibration method can be used effectively for the absolute evaluation of fission track ages of apatite.     

Characteristics of heavy ion tracks in bubble detectors

Characteristics of tracks created by heavy ions in bubble detectors have been studied in detail by using four types of super long (23 cm), self-made bubble detectors and six species of high energy heavy ions: ¹²C, ²⁸Si, ⁴⁰Ar, ⁵⁶Fe, ⁸⁴Kr and ¹³²Xe. The following characteristics of heavy ion tracks in bubble detectors have been recognized:

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The chemical etching of fission fragment tracks in natural fluorite

An experimental study of the mechanism for chemical etching of fission fragment tracks in the natural mineral fluorite is described. A systematic search showed that a 3:1 mixture by volume of sulphuric to hydrochloric acids was a most appropriate etchant. Experiments directed at determining the etching efficiency as a function of solvent temperature are also discussed. The preferential track etch ratioVt/Vg, the track length and the track density all depend upon the time and temperature of annealing.

It is variations of the fission track density in fluorite, with etching time and annealing temperature, which make possible an overall geophysical interpretation of annealing data for the mineral in terms of the paleoisotherm of its intrinsic fission track clock.

An interactive image analysis system INTIMAN, assembled for the swift and automatic readout of fission fragment track measurements, in both crystalline and non-crystalline materials, is described. Normal procedures for measuring and analyzing tracks are outlined.     

Effect of swift (∼100 MeV) heavy ion irradiation on surface morphology and electronic transport in Fe film on Si substrate

Fe film (∼50 nm) have been deposited on pSi substrate by electron beam evaporation technique. The bilayers have been irradiated by 100 MeV Fe⁷⁺ ions having fluences of 1 × 10¹³, 1 × 10¹⁴ and 5 × 10¹⁴ ions cm⁻². SEM study of the unirradiated devices show surface modifications having a annular structures. From XRD study of the bilayer, it is observed that grain size has reduced from 70 to 25 nm after the irradiation for a fluence of 1 × 10¹⁴ ions cm⁻². Moreover electronic transport data of the bilayer show practically no effect on the current flow for a fluence of 1 × 10¹³ ions cm⁻² irradiation whereas for 1 × 10¹⁴ ions cm⁻² fluence, there is very significant change in current flow (by two orders in magnitude) across the bilayer. However, for a higher fluence of irradiation 5 × 10¹⁴ ions cm⁻², the bilayer becomes highly resistive. It has been found from the above observations that the fluence of 1 × 10¹⁴ ions cm⁻² of swift heavy ion irradiation is a optimum fluence.     

集簇性DNA损伤在辐射研究中的进展

高LET重离子引起的集簇性DNA损伤会造成细胞突变、 癌变和凋亡。 促进肿瘤细胞凋亡一直是治愈肿瘤的出发点, 所以集簇性DNA损伤已经成为放射生物学领域研究的热点问题。 由于其提取和检测方法多样, 但并没有一个详细和完整的方案对集簇性DNA损伤进行透彻分析。 综述了集簇性DNA损伤的特点和详细讨论了集簇性DNA损伤最新研究进展, 简介了集簇性DNA损伤的研究方法, 以期为集簇性DNA损伤在放疗中的研究提供一些参考。 Clustered DNA damage which caused by high LET heavy ion radiation can lead to mutation, tumorigenesis and apoptosis. Promoting apoptosis of cancer cells is always the basis of cancer treatment. Clustered DNA damage has been the hot topic in radiobiology. The detect method is diversity, but there is not a detail and complete protocol to analyze clustered DNA damage. In order to provide reference for clustered DNA damage in the radiotherapy study, the clustered DNA damage characteristics, the latest progresses on clustered DNA damage and the detecting methods are reviewed and discussed in deteil in this paper.     

Track structure in polyethylene terephthalate irradiated by heavy ions: Let dependence of track diameter

The structure of latent tracks in polyethylene terephthalate is studied using chemical etching combined with a conductometric technique. Geometrical parameters of the latent tracks for the range of the electronic energy loss (dE/dx) between 3 to 24 keV/nm are estimated. The dependence of the track core and track halo size on the energy loss is analyzed.     

Effect of secondary electrons from latent tracks created in YBCO by swift heavy ion irradiation

Swift heavy ions (SHI) with electronic energy loss exceeding a value of 14.4 keVnm⁻¹ create amorphized latent tracks in YBCO type superconductors. In the low fluence regime of an ion beam where tracks do not overlap, a decrease of the superconducting transition temperature as probed through resistivity studies, is not expected due to availability of percolating current paths. The present study however shows T_c decrease by about 1–3 K in thin films of YBCO when irradiated by 250 MeVAg ions at 79 K at a fluence of 5×10¹⁰–1×10¹² ionscm⁻². The highest fluence used in the present study is three times less than the fluence where track overlapping becomes significant. The T_c tends to increase towards the preirradiation value on annealing the films at room temperature. To explain this unusual result, we consider the effect of ion irradiation in inducing materials modification not only through creation of amorphized latent tracks along the ion path, but also through creation of atomic disorder in the oxygen sublattice in the Cu–O chains of YBCO by the secondary electrons. These electrons are emitted radially from the tracks during the passage of the SHI. Considering the correlation between the charge state of copper and its oxygen coordination, we show in particular that the latter process is a consequence of the inelastic interaction of the SHI induced low-energy secondary electrons with the YBCO lattice, which result in chain oxygen disorder and T_c decrease.     

Combined field ion microscopy and transmission electron microscopy of heavy ion damage in tungsten

Abstract

A field ion microscopy (FIM) and transmission electron microscopy (TEM) investigation of radiation damage in tungsten after heavy ion bombardment has been carried out. Field ion specimens of tungsten were irradiated with 180–230 keV Xe⁺ ions. The irradiation doses were varied between 4 × 10¹¹ and 4 × 10¹² ions/cm². The irradiated specimens were examined in FIM. Experiments combining both TEM and FIM were performed in order to compare the results obtainable by these two methods. The distribution of defects visible by TEM was inhomogeneous. The influence of the imaging field in FIM on the defects visible in TEM is discussed.     

Impact of the displacement damage in channel and source/drain regions on the DC characteristics degradation in deep-submicron MOSFETs after heavy ion irradiation

This paper mainly reports the permanent impact of displacement damage induced by heavy-ion strikes on the deep-submicron MOSFETs.Upon the heavy ion track through the device,it can lead to displacement damage,including the vacancies and the interstitials.As the featured size of device scales down,the damage can change the dopant distribution in the channel and source/drain regions through the generation of radiation-induced defects and thus have significant impacts on their electrical characteristics.The measured results show that the radiation-induced damage can cause DC characteristics degradations including the threshold voltage,subthreshold swing,saturation drain current,transconductance,etc.The radiation-induced displacement damage may become the dominant issue while it was the secondary concern for the traditional devices after the heavy ion irradiation.The samples are also irradiated by Co-60 gamma ray for comparison with the heavy ion irradiation results.Corresponding explanations and analysis are discussed.