On quantitative determination of radon concentration by γ-ray spectrometry of aerosol filters

The problem of determining the ²²²Rn concentration in air from γ-ray spectra of radon progeny is solved using the aerosol filters method. The systematic error of the method due to incomplete collection of radon progeny is determined. It is shown that, when comparing the filter activity to the analytical calculation, the use of a 20-cm-diameter 20-cm-tall NaI(Tl) crystal and a 4−π geometry makes it possible to measure radon concentration with an accuracy of 20-30%. Original Russian Text ? A.Kh. Khokonov, M.B. Masaev, Yu.V. Savoiskii, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 1, pp. 142–144.     

A new method for measuring γ-ray energy at the internal calibration of a radioactive source

We developed a new method for measuring γ-ray energies in the internal calibration of a radioactive source under investigation. The measurements were carried out with the spectrometer of delayed coincidences and an optical delay line. This method allows the energies of the reference peak and the γ-ray peak under investigation to be compared, even if they are close or coincide. The possibility of precise γ-ray energy measurements is illustrated with⁶⁰Co and¹⁵⁴Eu isotopes.     

Summation of pulses in γ-ray spectra

It is shown that peaks formed in -ray spectra by summing the pulses due to cascades can be used to determine both the activity of the radiation source and the efficiency of detecting the rays. Possible sources of errors in determining these quantities were investigated. This method may be used to measure the cross sections of nuclear reactions, to analyze the background radiation when searching for rare decays, and in other applications.Translated from Pribory i Tekhnika Eksperimenta, No. 1, 2005, pp. 58–61.Original Russian Text Copyright ¢ 2004 by Gromov, Fominykh, Chumin, Samatov.     

Quasi-differentiation method for forming anti-Compton γ-ray spectra

A method for forming anti-Compton γ-ray spectra is considered. The method is based on the quasi-differentiation of experimental γ-spectra according to the peak width.     

Comparing the time-of-fight techniques in a high-energy γ-ray telescope

The use of the time–coordinate compensation technique in detectors of the time-of-flight (TOF) system of a typical high-energy γ-ray telescope is considered. Detection of γ rays with energies of 10 and 1000 GeV by the TOF system of the telescope is simulated. Two variants of the TOF system design with and without the use of the time–coordinate compensation technique are compared. One of the techniques is used in each variant in both detectors of the TOF system. For both variants, the TOF spectra of secondary particles produced in the telescope converter are calculated. It is shown that the use of the coordinate compensation method is advantageous in the detection of γ rays with an energy of 1000 GeV.     

An adaptive γ-ray spectrometer with a high event processing rate

A fast γ-ray spectrometer adaptable to the scintillator type is described. This spectrometer is capable of processing a γ-ray energy spectrum (with a resolution of <4% in the energy range from 20 keV to 10 MeV) in a sequence of time intervals in the real-time mode at a counting rate of up to 10⁶ cps. Digitization of the detector signals by a 14-bit ADC with a sampling rate of 64 MHz and real-time data stream processing are used to separate overlapping events and correctly generate energy spectra.     

Radiation-tolerant X- and γ-ray detectors

Radiation-tolerant X-ray detectors capable of operating in vacuum, a low-voltage ionization chamber, and a γ detector, as well as a noise compensation system allowing location of all electronic devices at a distance of at least 70 m from the detectors, are described. Owing to the simplicity of their design, these detectors can be adapted for any specific conditions. These detectors are intended for operation in high- intensity γ-ray and neutron fields; in particular, they can be used on the ITER tokamak reactor.     

A technique for selecting γ rays with energies above 50 GeV from the background of charged particles in the GAMMA-400 space-based γ-ray telescope

The task of selecting neutral γ rays from the background of charged particle fluxes, which arises in investigation of high-energy (>50 GeV) cosmic rays, is complicated by the presence of the backsplash effect. The backsplash is composed of a great number of low-energy (~1 MeV) particles produced in an electromagnetic shower being developed in the calorimeter of the γ-ray telescope. A technique of charged particle rejection using an anticoincidence system has been developed. A method for discriminating events of charged particle detection from γ-ray detection events accompanied by the backsplash phenomenon is proposed. This method is based on the difference of the signals in time and makes it possible to maintain a high detection efficiency even for high-energy γ rays.     

Development of a Setup for the Discrimination of β+ and γ Rays

Abstract

A β⁺–γ discrimination set‐up was developed and applied to the ²²Na radioisotope. The radioisotope emits positrons (β⁺) and these positrons create γ rays by annihilating with electrons. These annihilation γ rays were used here, and the discrimination between these positrons and γ rays was investigated by the coincidence measurement between time signals and the energy signals. The detection system presented here uses a 3 inch (diameter) by 3 inch (length) NaI(Tl) inorganic scintillation detector for γ detection and 3 inch (diameter) by 3 inch (length) plastic scintillation detector for β⁺ detection.     

Development of a time-of-flight measurement technique in plasma induced by a СO<Subscript>2</Subscript> laser

Experiments on the irradiation of a carbon target with СО₂-laser pulses in the free-running mode at a radiation-flux density of 1.3 × 10¹¹ W/cm² and the time-of-flight technique for measuring the characteristics of the plasma ion component are described. The characteristics of the ion component of plasma that expands along the normal to the target and the statistical spread of the mean values were obtained. As a result of the measurements, the energy spectra of the plasma expansion and the partial ion currents at a chosen distance of the plasma drift from the target were reconstructed. The high time resolution of this technique made it possible to reconstruct the escape times of individual groups of ions from a heated region on the scale of the duration of the heating laser pulse.     

Development of a combined tension–torsion experiment for calibration of ductile fracture models under conditions of low triaxiality

Developments in computational mechanics have given engineers tools to predict the evolution of damage in complex structures. Damage models have been developed that relate failure strain to stress triaxiality and Lode angle. Calibration of these models has traditionally relied on specimens that exhibit high triaxiality and limited Lode angle. This paper presents a specimen that can be tested in combined tension and torsion to achieve low triaxiality over a range of Lode angle. Numerical analysis of the specimen shows that it exhibits uniformity of stress–strain and stable values of triaxiality and Lode angle as plastic strain develops, both of which are desirable characteristics for calibration of ductile failure models. The design of a new displacement and rotation gage is presented that allows non-contact measurement at the gage section. Experimental results are used to develop the failure surface for 5083 aluminum.     

AIWIN—a fast and jigless inspection technique for machined parts

Precision inspection of manufactured components having multiple complex surfaces and variable tolerance definition is an involved, complex and time-consuming function. In routine practice, a jig is used to present the part in a known reference frame to carry out the inspection process. Jigs involve both time and cost in their development, manufacture and use. This paper describes ‘as is where is inspection’ (AIWIN), a new automated inspection technique that accelerates the inspection process by carrying out a fast registration procedure and establishing a quick correspondence between the part to inspect and its CAD geometry. The main challenge in doing away with a jig is that the inspection reference frame could be far removed from the CAD frame. Traditional techniques based on iterative closest point (ICP) or Newton methods require either a large number of iterations for convergence or fail in such a situation. A two-step coarse registration process is proposed to provide a good initial guess for a modified ICP algorithm developed earlier (Ravishankar et al., Int J Adv Manuf Technol 46(1–4):227–236, 2010). The first step uses a calibrated sphere for local hard registration and fixing the translation error. This transformation locates the centre for the sphere in the CAD frame. In the second step, the inverse transformation (involving pure rotation about multiple axes) required to align the inspection points measured on the manufactured part with the CAD point dataset of the model is determined and enforced. This completes the coarse registration enabling fast convergence of the modified ICP algorithm. The new technique has been implemented on complex freeform machined components and the inspection results clearly show that the process is precise and reliable with rapid convergence.     

The 12C(3He,pγ)14N reaction cross section for γ-ray spectroscopy simulation of fusion plasmas

High resolution γ-ray spectroscopy measurements were performed in JET (3He)D plasmas with high energy ion populations driven by radio-frequency (RF) heating. One of the first reactions investigated was 12C(3He,pγ)14N, which was observed at low 3He concentrations. In order to interpret the measurements in this work, cross section data for the 12C(3He,pγ)14N reaction are evaluated. Available data for the population of excited states in 14N up to the eighth level are assessed in the range E(3He) = 0–5?MeV. Discrepancies and gaps in the database have been solved by means of interpolations and consistency analysis. The evaluated cross section data are used to predict the intensity ratio of characteristic 2.31 and 1.63 MeV γ-rays.     

Development of a Stereolithography File Interface with ArtCAM™

This paper presents the technique used for converting a 3D ArtCAM™ relief file into the stereolithography (STL) format. This 3D file is obtained from a 2D picture using a 3D CNC engraving software called ArtCAM™. The problem is to convert the 3D relief files into an STL format without compromising the accuracy and details of therelief. This paper discusses the size of the files which have been converted, and steps taken to reduce the file size by reducing the number of triangles or facets in the STL file. The discussion involves the verification of the converted model by comparing it with the original relief. The problems associated with the reduction of triangles when the file has been converted to STL format are also discussed.     

Development of a 635 nm-Laser Diode Spectrometer for Continuous Monitoring of Amino Nitrogen in the Beet Sugar Industry

Abstract

The quality of sugar beet is affected by harmful nitrogen compounds. Although nitrogen is one of the essential elements for plants, introduction of excess nitrogen as fertilizer to the soil increases the nitrogen containing compounds in beet which deteriorates the quality of sugar production. Hence, the concentration of soluble nitrogen in beets was monitored as a routine process in the sugar industry. In this work, a low cost, but very long life time laser diode spectrometer, was developed for continuous monitoring of amino nitrogen compounds in sugar beets. A laser diode source emits monochromatic light at 635 nm which is the maximum of absorption spectrum of Cu(II)-glutamine complex. A standard solution of Cu(II) ion and glutamine was prepared at pH = 6.0 to calibrate the laser diode spectrometer. The formation of Cu(II)-glutamine complex was examined at pH = 5.0, 6.0, and 7.0 by a continuous variations method and we found a monovalent complex, Cu(II)(glutamine) at pH = 6.0, and a divalent complex, Cu(II)(glutamine)₂ at pH = 7.0. A continuous mixing system with a peristaltic pump and tubing was set for monitoring of harmful nitrogen in beets, besides sugar determination with a polarimeter and Na and K measurement with a flame photometer, synchronously. The calibration of the laser diode spectrometer yielded a linear correlation coefficient of R² = 0.999. A negative correlation between sugar digestion and amino nitrogen content of sugar beets was found, with a correlation coefficient of R² = 0.807.     

Influence of friction during forming processes—a study using a numerical simulation technique

Friction has an important influence in metal forming operations, as it contributes to the success or otherwise of the process. In the present investigation, the effect of friction on metal forming was studied by simulating compression tests on cylindrical Al-Mg alloy using the finite element method (FEM) technique. Three kinds of compression tests were considered wherein a constant coefficient of friction was employed at the upper die–work-piece interface. However, the coefficient of friction between the lower die–work-piece interfaces was varied in the tests. The simulation results showed that a difference in metal flow occurs near the interfaces owing to the differences in the coefficient of friction. It was concluded that the variations in the coefficient of friction between the dies and the work-piece directly affect the stress distribution and shape of the work-piece, having implications on the microstructure of the material being processed.     

Present Situation and Forecast for Development of Rubber Injection Press

The rubber injection moulding machinery is one of the three major moulding machines in the industrial moldedrubber articles. It is only inferior to the rubber curing press （hot molding machine） in quantity, but is far higher than the rubber transfer injection molding machine （injection moulding machine）, and occupies the 1/4 above share of the total amount. At present, the capacity of the rubber injection moulding machine all over the world estimates for 30,000-40,000 at least, the amount of rubber consumed is above 60% - 70% of the molded rubber articles, and became the main equipment of the rubber products for automobile, electronics and so on.     

Development of a radiative transfer model for the determination of toxic gases by Fourier transform–infrared spectroscopy with a support vector machine algorithm

Abstract

This report describes a radiative transfer model for Fourier transform-infrared (FT-IR) spectroscopy to create close-to-reality toxic gas spectra by reflecting the unique spectral responses of detectors and using the atmospheric radiative transfer code, MODTRAN. This system can be highly useful in overcoming the limitations for measuring toxic gases in open environments. The emulated gas spectra can be used to train support vector machine (SVM) for chemical gas detection. Its detection performance is evaluated with nerve agents (tabun, sarin, soman, and cyclosarin) and a simulant gas (sulfur hexafluoride) for indoor and outdoor experiments by using two off-the-shelf FT-IR gas detectors. The experimental results show that the proposed SVM algorithm successfully detected and classified targeted gases while reducing false negative and false positive detection rates.     

Monitoring of <Superscript>235</Superscript>U content of fuel assemblies for nuclear reactors based on neutron and γ-ray scintillation detector systems

A model of the setup for determining the ²³⁵U content of a fuel assembly for WWER-440 reactors is described. The setup operates based on the digital technology for discriminating neutron and photon scintillation responses. An AmLi source is used as an external neutron source. A three-channel system for detecting fission particle coincidences is based on EJ-309 scintillators. A set of digital codes for obtaining and analyzing neutron-neutron (nn), neutron-γ (nγ), and γ-γ (γγ) coincidences has been developed. Dependences of double coincidences have been experimentally obtained and analyzed with the aim of determining the ²³⁵U content of the fuel assembly. It is shown that fission neutrons and coincidences of the nn and nn + γn + nγ types are the best informative parameters for the ²³⁵U content of the fuel assembly.