Application of solid state track recorders for neutron spectra measurements in a reactor irradiation facility

Abstract

In connection with the IAEA-neutron seed irradiation Programme, a standard neutron irradiation facility has been constructed. The application of solid state track recorders for fast neutron spectra measurements inside this facility is discussed. Fissionable targets of ²³⁵U, ²³⁹Pu, ²³⁷Np, ²³⁸W and ²³²Th will be used, an approximative solution for the incident neutron spectrum will be obtained by a five-group method.     

Enrichment of Lithium,Potassium, Copper,and Uranium Isotopes by Electromigration in a Cation Exchange Membrane

The ion exchange membrane can be used as an effective medium of electromigration for the separation of isotopes by the following reasons.     

Bestimmung der Homogenität von Legierungen mittels Autoradiographie and Aktivierungsanalyse

An für Konstruktionselemente verwendente verwendete Legierungen werden in Abhängigkeit von ihrer Verwendung folgende Anforderungen gestellt: hole Festigkeitskoeffizienten, erhöhte Temperaturbeständigkeit, erhöhte Korrosionbeständigketi gegen Chemikalien, erhöhte Verschleißbeständigkeit u. a. Chemische Heterogenität ist Ursache für Korrosionserscheinungen, Einleitung ungünstiger Reaktionen sowie Herabsetzung der örtlichen Reibfestigkeit und bewirkt damit eine Erniedrigung der Güteeigenschaften der Legierung. Einer der grundsätzlichen Wege, diesen Erscheinungen vorzubeugen, ist ein möglichst hoher Homogenitätsgrad der Legierung.     

Tabulated Values of Thermal Diffusion Factors for Various Isotopic Gaseous Mixtures

Numerical Values of the Thermal Diffusion Factors α_T have been calculated for the isotope systems of H₂, He, CO, N₂, O₂ CH₄ as a function of reduced temperature T^* in the Kihara first and second approximations for both the exp-6 molecular model and the Lennard-Jones (12, 6) model.     

Low-temperature electrical resistivity characteristics of fast-neutron-irradiated CdS: New concepts in neutron detection

Time dependent electrical resistivity changes at low temperature in fast-neutron irradiated CdS have been studied. The experiments were on low-resistivity single crystals, and the electrical changes result from radioactive decay effects induced by the fast-neutron irradiation. Results show that following neutron irradiation and upon lowering the sample temperature, the resistivity decreases with time and approaches a stable value. These effects are attributed to trapping phenomena, and can be erased by increasing the temperature. The time dependent electrical changes associated with radioactive decay provide a new means for neutron detection.     

Studies on the Preparation of 113Sn-113mIn Generators

Presently available ^113mSn.^113mIn generators use high specific activity ¹¹³Sn which cannot be produced in low and medium flux research reactors even with enriched ¹¹²Sn. This paper describes a method of preparing ¹¹²Sn.^113mIn generators using ^ll3Sn of relatively low specific activity (2—3 Ci/g) obtained by irradiation of enriched ¹¹²Sn in CIRUS. In this modified procedure, ¹¹³SnCl₄ is firmly adsorbed on hydrous zirconia from 3—4 M NaCl solutions of pH 1.3 to 1.5 and the elution of ^113mIn is effected by dilute HCl. The generator yields 70% of the theoretically available ^ll3mIn activity. ¹¹³Sn breakthrough has been consistantly less than 0.01% of the ^113mIn activity. Stable zirconium contamination in the eluate has been estimated to be less than 1 ppm. The performance characteristics of different varieties of hydrous zirconia have been studied to evaluate the optimum tin loading, indium elution and soluble zirconium contamination. Generators containing upto 700 mCi of tin-113 have been prepared yielding pure indium-113m suitable for medical use.     

Verteilung von Wismut-Spuren im Korngrenzenbereich von technischem Kupfer

Kupferproben mit Gehalten von 40 bis 100 ppm Wismut, die bei 580 °C eine halbe Stunde geglüht wurden, zeigen eine groβe Anreicherung dieses Elements im Bereich der Korngrenzen. Die Abnahme des Anreicherungsgrades mit fallender Bi-Ge-halten verläuft nicht proportional. Eine Glühung bei 750 °C führt zu einer besseren Verteilung bzw. geringeren Bi-Anreicherung in diesem Bereich.     

PNP输入双极运算放大器在不同辐射环境下的辐射效应和退火特性

研究了PNP输入双极运算放大器LM837在1 MeV电子和⁶⁰Coγ源两种不同辐射环境中的响应特性和变化规律. 分析了不同偏置状态下其电离辐照敏感参数在辐照后三种温度 (室温, 100 ℃, 125 ℃)下随时间变化的关系, 讨论了引起电参数失效的机理. 结果表明: 1 MeV 电子辐照LM837引起的损伤主要是电离损伤, 并且在正偏情况下比⁶⁰Coγ源辐照造成的损伤大; 辐照过程中, 不同辐照源正偏条件下的偏置电流变化都比零偏时微大; 在不同的辐照源下, LM837辐照后的退火行为都与温度有较大的依赖关系, 而这种关系与辐照感生的界面态密度增长直接相关. 关键词： PNP 输入双极运算放大器 60Coγ源')" href="#">电子和⁶⁰Coγ源 偏置条件 退火     

Nuklearpharmaka — Ihre Entwicklung,Präparation und Anwendungsmöglichkeiten

Radioaktiv markierte Präparate haben in denletzten Jahren in schnell zunehmendem Maße Eingang in die klinische Medizin gefunden. Sie sind beieiner Reihe von Indikationen schon jetzt außerordentlich wertvolle Hilfsmittel bei der Diagnose, besonders bei der Prüfung von Organfunktionen.     

Buchbesprechungen

Chromatographic separation of oleic acid-I¹³¹ and triolein-I¹³¹ from free iodide has been studied in a number of solvents on ordinary chromatographic paper as well as paper impregnated with various heavy metals. The latter help in firmly fixing the iodide at the point of spotting. Copper and lead oleates which can form on the impregnated papers move along with oleic acid. Bismuth, mercuric, palladium, and silver oleates are not formed on the impregnated papers.     

Luminescence studies on photostimulable phosphor CsBr:Eu2+

Photostimulable phosphor CsBr:Eu²⁺ is prepared through a solid-state reaction. The effect of annealing atmosphere on photoluminescence and photostimulated luminescence was investigated. Optimum luminescence intensity was obtained when samples were prepared at 350°C in air atmosphere. The effect of irradiation of gamma and neutron had resulted in the formation of optically stimulable traps with different trap depths. The role of monovalent and divalent dopants on thermoluminescence dosimetric properties has been discussed.     

Substoichiometric Determation of Silver Traces in Palladium with Adsorptive Sampling

A substoichiometic analytical method of high sensitivity combined with adsorptive sampling has been worked out for the determination of traces of silver in palladium making use of the selective deposition of microquantities of silver from aqueous solutions of palladium salts on cathodically polarized platioum surfaces. The stability and reporducibility of the saturation values of deposited silver are practially independent of the content and concentration of silver and palladium in the solution. The sensitivity proved to be 0.01 ppm, the accuracy ± 30 per cent.     

Radiation effects on luminescent and structural properties of YPO4: Pr3+ nanophosphors

ABSTRACT

YPO₄ phosphors doped with trivalent ion Pr³⁺ were prepared by sol–gel method and treated with different doses of gamma radiation, from 0.25 MGy to 4 MGy. Effects of radiation on morphology, structure and luminescent properties were analyzed. Also, the influence of radiation on the change in the color of the samples was examined. The color efficiency of powders was evaluated by colorimetric analysis (CIE and L * a * b system). It has been observed that powders change color under the influence of radiation, i.e. they pass from white to pinkish red. Also, it has been determined that the radiation affects morphology change, as the particle size increases with increasing of the radiation dose. With the increase in the radiation dose, the emission intensity of samples decreases. The structure remains almost unchanged after irradiation, and the intensity constantly decreases with increasing of dose.     

Green emitting long lasting phosphorescence (LLP) properties of Mg2SnO4:Mn phosphor

A novel long-lasting phosphorescence phosphor, Mn²⁺-activated Mg₂SnO₄, has been synthesized and its optical properties have been investigated. The Mg₂SnO₄:Mn²⁺ emits green light with high luminance, upon UV irradiation, centered at 499 nm from the spin forbidden transitions of the d-electrons in Mn²⁺ ions. The CIE chromaticity coordinates of the Mg₂SnO₄:Mn²⁺ phosphor are x=0.0875 and y=0.6083 under 254 nm UV excitation. The phosphorescence can be observed by the naked eyes (0.32 mcd/m²) in the dark clearly for over 5 h after the 5 min UV irradiation. Thermoluminescence has been studied and the mechanism of the long-lasting phosphorescence has been discussed.     

Initial Search for Triggered Gamma Emission from 178Hfm2 Using the YSU Miniball Array

Experiments with the long-lived, high-K isomer ¹⁷⁸Hf^m2 have been recognized as intriguing tests of multi-quasiparticle state structures and their interactions with external radiation. A triggered release of the energy stored by this isomer, 2.5 MeV per nucleus or 1.2 GJ/gram, in the form of a gamma-ray burst might prove valuable for numerous applications. The observation of “accelerated” decay of ¹⁷⁸Hf^m2 during irradiation by 90-keV bremsstrahlung has already been reported, but with poor statistical accuracy due to the experimental approach. That approach employed single Ge detectors to seek increases in the areas of peaks at energies corresponding to transitions in the spontaneous decay of the isomer. The need for better quality data to confirm those results has motivated the development of improved detection concepts. One such concept was utilized here to perform an initial search for low-energy (<20 keV) triggered gamma emission from ¹⁷⁸Hf^m2 using the YSU miniball detector array. This revised version was published online in August 2006 with corrections to the Cover Date.     

On the Non-Destructive Neutron Activation Method for the Determination of Lithium,Based on a Secondary Nuclear Reaction with Tritons

The purpose of the present article is to make clearer the possibilities of the non-destructive method for neutron activation determination of lithium without the use of apparatus or measurement of gamma-gamma coincidences. The most important sources of error has been investigated and it was shown how these could be eliminated. The sensitivity of the non-destructive method without using gamma-gamma coincidence was found to be about 10^?8g Li. The presence of sodium in the samples in fact does not impair the accuracy of the measurement when the quantity of sodium is not higher than 10^?5 g. The error rises to ll% when the quantity of sodium present in the sample is about 10^?4g. The accuracy of the destructive and non-destructive neutron activation method for the determination of lithium could also be influenced by certain parallel nuclear reactions with tritons. In this connection the influence of sulphur on the neutron activation determination of lithium was investigated. A formula for calculating the optimal cooling time and the counting time of the samples ivas established, designed to diminish the influence of sulphur on the results of the analysis.     

New spectroscopic studies of the Comet-Tail (AΠi-XΣ) system of the CO molecule

In the electronic emission spectrum of the ¹²C¹⁶O⁺ molecule, 11 bands of the Comet-Tail (A²Π_i-X²Σ⁺) system have been recorded and analyzed. Spin splitting in most of the observed lines of the 0-2, 1-0, 2-0, 2-1, 3-0, 4-0, 4-2, 6-0, 7-0, 7-1, and 8-1 bands, comprising nearly 3400 lines, has been recorded under high resolution by conventional spectroscopy. The rotational analysis of bands has been performed by nonlinear least-squares procedures and by means of effective Hamiltonians of Brown et al. and the rovibronic structure parameters have been obtained. The data of bands of the A-X system and earlier analyzed bands of the B-X and B-A systems have been merged together. As a result of this global fit, the state of information about the energy structure has been significantly enlarged for the A state and enlarged and improved for the X state. Also RKR potential curves for both states and Franck-Condon factors as well as r-centroids of the Comet-Tail system of CO⁺ have been calculated.     

Fluorescence and persistent spectral hole burning of Eu in Ge-Ga-S-KBr glasses

Fluorescence and efficient persistent spectral hole burning of Eu³⁺ at 77 K were observed in chalcohalide glasses. The depth of the hole was approximately 30% after a burning process of 1 min with 50 mW power, and it was completely erased with Ar⁺ laser irradiation. The hole survived room temperature heat treatment and showed good thermal stability. The hole-burning mechanism was most probably the photo-reduction of Eu³⁺→Eu²⁺. Fluorescence from Eu³⁺ decreased with increasing temperature and disappeared at the temperature above ∼130 K.     

Effect of γ-irradiation on structural,morphological and luminescence properties of cerium-doped Y3Al5O12 nano-material

ABSTRACT

Cerium-doped yttrium aluminum garnet (YAG: Ce³⁺) nanopowder phosphors have been elaborated by sol–gel process and annealed at 900°C for 2?h. The prepared phosphors were exposed to gamma radiation, using ⁶⁰Co source, at different doses ranging from 5 to 100?kGy. The influence of γ-irradiation on the structural, morphological and luminescence properties of YAG: Ce³⁺ phosphors were investigated in detail by X-ray diffraction, ?eld emission scanning electron microscopy (FESEM), Fourier transforms infrared spectroscopy (FTIR) and photoluminescence measurements. The XRD analysis confirmed the presence of single cubic phase for all samples of YAG: Ce³⁺ nanophosphors independent of γ-rays dose. FESEM micrograph results revealed that the particles present flate-like shapes and high density of dislocation for sample irradiated at 100?kGy of γ-ray. The YAG: Ce³⁺ nanophosphors showed broad green–yellow emission band in the range of 450–700?nm with maximum intensity at 538?nm assigned to the 5d → 4f transitions of Ce³⁺ ion. The emission intensity of YAG: Ce³⁺ phosphors vary with the γ-ray irradiation and reach the maximum for sample irradiated to a dose of 25?kGy. The variation of luminescence intensity is related to the crystallite size and Ce⁴⁺ ions content in YAG host nanomaterial.     

Highly sensitive absorption spectroscopy of carbon dioxide by ICLAS-VeCSEL between 8800 and 9530 cm

The absorption spectrum of carbon dioxide has been studied between 8800 and 9530 cm⁻¹ by intracavity laser absorption spectroscopy based on a vertical external cavity surface emitting lasers (VeCSEL). Previous laboratory spectra at high resolution were nearly absent in the considered spectral region. Experiments were carried with natural carbon dioxide and with ¹³C enriched carbon dioxide leading to the determination of the rovibrational parameters of a total of 15 very weak vibrational transitions, including two bands of the ¹⁶O¹³C¹⁸O isotopologue. The observed transitions are assigned to components of the 2ν₁ + 3ν₃ triad and of the much weaker 5ν₁ + ν₃ hexad. Our measured line positions are found in excellent agreement with the predictions of the effective Hamiltonians developed for ¹²C¹⁶O₂ and ¹³C¹⁶O₂ but significant deviations were evidenced for the ¹⁶O¹³C¹⁸O minor isotopologue. The relative band intensities within each polyad are also discussed on the basis of the effective Hamiltonian model.