Gap width measurements in fuel elements

The analysis of 11 neutron radiographs, five of pin CEP-E1 no. 4 and six of pin CEP-E1 no. 7 are presented. The dimensions of the gaps between adjacent pellets were determined by three methods: projection microscopy measurements, the derivative method and the convolution method. The errors associated with the gap width measurements were in some cases over 100%.     

T颗粒X线胶片和矽肺X线摄影

本文以实例表明用柯达T颗粒感绿X线胶片配合专用的硫氧化钆/铽稀土元素绿增感屏进行矽肺肺摄影可以取得优越的临床诊断效果:细微结构清晰、信息量增加,有利于早期病变的检出。X线投照量仅需作对比用的常规富士感蓝X线胶片和钨屏组合的五分之一至三分之一。     

Limitations of a relaxation oscillator in capacitance measurements

Oscillation periods of a relaxation oscillator consisting of an op-amp-based integrator and a comparator are measured over a wide range of RC integration constants, and the results are compared with theoretical values derived in terms of the finite gain-bandwidth (GB) product and the slew rate of an op-amp and the response delay of a comparator. The comparison validates the theoretical derivation which gives the design criteria of a relaxation oscillator for capacitance measurements and sensor signal processing     

Accelerator-based neutron tomography cooperating with X-ray radiography

Neutron resonance absorption spectroscopy (N-RAS) using a pulsed neutron source can be applied to time-of-flight (TOF) radiography, and the obtained parameters from the peak shape analysis can be reconstructed as the tomograms of nuclide distributions using computed tomography (CT). The problem is that the available spatial resolution is not sufficient for radiography imaging. In this study, we combined neutron and X-ray radiographies to improve the quantitative reconstruction of the neutron tomogram. The accelerator-based neutron source emits X-rays (or gamma-rays) at the same time the neutron pulse is emitted. We utilized the X-ray beam from the neutron source to obtain X-ray radiogram on the same beam line with neutron radiography and then reconstructed the neutron tomogram quantitatively with the help of a detailed sample internal structure obtained from the X-ray radiogram. We calculated the nuclide number density distribution tomogram using a statistical reconstruction procedure, which was easy to include in the structure model during the reconstruction. The obtained result of nuclide number density distribution showed good coincidence with the original object number density.     

On the optimum width of the separating gap in liquid thermodiffusion columns

Based on earlier developed models of the partition process with attendant stray convection, the authors make recommendations on how the efficiency of liquid thermodiffusion columns may be raised.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 22, No. 5, pp. 825–828, May, 1972.     

狭缝宽度及坩埚半径对分离结晶法制备CdZnTe晶体的影响

借助有限元法,在常重力条件下对分离结晶过程进行全局数值模拟,研究了狭缝宽度及坩埚半径对CdZnTe晶体生长过程中整体传热与流动特性的影响。模拟结果表明系统内传热特性、熔体流型与狭缝宽度及坩埚半径密切相关:(1)狭缝宽度对分离结晶有决定性的作用,当狭缝宽度较小时,气-液弯界面两端的温差很小,导致增大晶体重新粘附于坩埚壁面的风险;随着狭缝宽度的增大,流动不稳定性增加,很难保持稳定的气-液弯界面形状,增加了实现晶体稳定生长的难度;(2)随着坩埚半径增大,Marangoni对流对熔体流动影响逐渐增大,结晶界面附近的熔体流动不稳定性增加,这不利于晶体的稳定生长。     

Study of hydrogen effusion in austenitic stainless steel by time-resolved in-situ measurements using neutron radiography

The purpose of the present study was to show the feasibility of measuring hydrogen effusion in austenitic stainless steel (1.4301) using neutron radiography at the facility ANTARES of the research reactor FRM II of the Technische Universität München. This method is appropriate to measure in-situ hydrogen effusion for hydrogen concentrations as small as 20 ppm_H. Experiments were carried out in the temperature range from room temperature up to 533 K. The measurement principle is based on the parallel comparison of electrochemically hydrogen charged specimen with hydrogen-free reference specimen at the same temperature. This allows the determination of the hydrogen concentration in the specimens as a function of time and temperature. Separate hot carrier gas extraction experiments using the same temperature-time profiles as the radiography experiments have been used to calibrate the grey values of the neutron transmission images into hydrogen concentrations. It can be stated that the hydrogen effusion correlates with the specimen temperature.     

Pionic X-ray measurements of biological materials

Ratios of pion atomic capture in carbon and oxygen, determined from measurements of X-rays emitted when negative pions stop in a material, are presented for selected acetates and a set of sugar isomers (C₆H₁₂O₆).     

Radiation measurements around X-ray cabinet systems

Security personnel who operate X-ray units for the control of hand luggage and personal items at airports are generally not under dosimetric surveillance. A significant increase in the number of inspected items per passenger, due to rigorous air traffic security measures, raises a question of extended exposure of these workers to scattered X-ray radiation. A new approach to investigating directions of breaches of scattered X-ray radiation in the area near to an X-ray cabinet system, which is based on using active electronic dosemeters is presented. Influence of the increase in the number of inspected items in time on the dose rate is described. Time-dependent dose rates have showed a very good correlation with passengers undergoing security control prior to boarding an airplane. Measurements confirmed that an increase in the dose rate, coinciding with rush hours, was caused by scattered radiation passing through incompletely closed lead curtains. It is found that the doses at the entrance to the inspection tunnel are 50% higher than those at the exit, which is a consequence of inherent operational characteristics of X-ray cabinet systems.     

Flash X-ray radiography source based on plasma-filled rod pinch diode

Results of experiments on the formation of a high-power focused electron beam in a plasma-filled rod pinch diode driven by a high-current MIG generator (maximum voltage, 1.3 MV; impedance, 0.65 Ω) are presented. The proposed diode with a sharpened 1.5-mm-thick tungsten rod anode provides an X-ray source for flash radiography with a size of ∼1 mm, which is capable of producing a radiation dose of 2.4 rad per pulse at a distance of 1 m. The results of comparative experiments with and without plasma injection into the diode are presented.     

Metrology issues in thin ONO stacks measurements by spectroscopic ellipsometry and X-ray reflectivity

We performed X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) analysis of several ONO stacks with different deposition conditions. TEM was also used as reference technique. In the energy range from 1.5 to 6.5 eV, SE analysis shows a correlation between bottom and top oxide thickness. The small electron density difference between Si and SiO₂ makes the SiO₂/Si interface determination difficult to estimate by XRR. By etch profiling we observed a relatively large extension of the oxide/nitride interfaces. Comparing the results of both techniques, we have observed major differences in thickness estimation. Most of these differences can be attributed to an estimation and weighting of the interfaces among the different techniques are considered in this paper.     

X-ray measurements in the atmospheric environment of Brazil

X-ray measurements using balloon-borne omnidirectional scintillation detectors were done in São José dos Campos, Brazil, on April 14 and December 18, 1981. The atmospheric, diffuse and magnetospheric components were measured. The atmospheric and diffuse components were found to be of the same order of magnitude in this region. The magnetospheric component showed to be strongly dependent on magnetic activity. Analysis of variations of this component suggests the occurrence of wave-particle interactions in this region in association with the South Atlantic magnetic anomaly (SAMA).     

The additional dose to radiosensitive organs caused by using under-collimated X-ray beams in neonatal intensive care radiography

Radiographic technique and exposure parameters were recorded in five Israeli Neonatal Intensive Care Units for chest, abdomen and both chest and abdomen X-ray examinations. Equivalent dose and effective dose values were calculated according to actual examination field size borders and proper technique field size recommendations using PCXMC, a PC-based Monte Carlo program. Exposure of larger than required body areas resulted in an increase of the organ doses by factors of up to 162 (testes), 162 (thyroid) and 8 (thyroid) for chest, abdomen and both chest and abdomen examinations, respectively. These exposures increased the average effective dose by factors of 2.0, 1.9 and 1.3 for the chest, abdomen and both chest and abdomen examinations, respectively. Differences in exposure parameters were found between the different neonatal intensive care units-tube voltage, current-time product and focal to skin distance differences up to 13, 44 and 22%, respectively. Reduction of at least 50% of neonate exposure is feasible and can be implemented using existing methodology without any additional costs.     

Use of artificial neural networks on optical track width measurements

We have demonstrated recently that, by using an ultrastable optical interferometer together with artificial neural networks (ANNs), track widths down to 60 nm can be measured with a 0.3 NA objective lens. We investigate the effective conditions for training ANNs. Experimental results will be used to show the characteristics of the training samples and the data format of the ANN inputs required to produce suitably trained ANNs. Results obtained with networks measuring double tracks, and classifying different structures, will be presented to illustrate the capability of the technique. We include a discussion on expansion of the application areas of the system, allowing it to be used as a general purpose instrument.     

Adsorption of thin isobutane films on silicon investigated by X-ray reflectivity measurements

An X-ray reflectivity study of the silicon isobutane interface is presented. Thin isobutane films were adsorbed on a silicon wafer and their film thickness was measured as a function of pressure in order to determine the effective Hamaker constant which is a proportion of the coupling between substrate and adsorbed film. A comparison with theoretical expressions of the effective Hamaker constant is given.     

Texture and secondary extinction measurements in Al\Ti stratified films by X-ray diffraction

In the present work the effects of secondary extinction has been studied using standard X-ray diffractometer and texture diffractometer techniques. For this purpose the texture of Al\Ti stratified films have been measured and evaluated. It is shown that these films have a very sharp single component texture. Therefore the evaluation and the interpretation of the measurement data is only possible when secondary extinction correction is carried out. The effect of secondary extinction is evaluated on the 111 pole figures of the stratified films with different layer pair numbers. The volume fraction of the main texture component is calculated from pole figures and it is shown that the grains of the films are practically completely oriented with 111 crystallographic direction parallel to the film surface normal. Moreover in the case of pole density measurements the secondary extinction values themselves are simultaneously calculated.     

X-ray imaging plate using CsBr:Eu phosphors for computed radiography

It is shown that X-ray-irradiated Eu-doped CsBr (CsBr:Eu) exhibits intense photostimulated luminescence (PSL). The peak wavelengths of PSL emission and stimulation spectra of CsBr:Eu phosphor ceramic samples are 450 and 690 nm, respectively. The dependence of PSL properties on preparing conditions of phosphor ceramic samples, such as Eu concentration, sintering temperature and sintering time, is studied. It is found that the PSL intensity of CsBr:Eu phosphor ceramics fabricated under optimum preparation condition is higher than that of commercially available imaging plates (IP) using BaFBr:Eu and BaFI:Eu. The image quality of the IP using CsBr:Eu phosphor film is better than that of commercially available IP.