A new gamma-ray spectrum catalog and library for PGAA

New measurements have been performed at the PGAA facility at the Budapest Research Reactor (BRR) in order to create a prompt -ray catalog for qualitative and quantitative analysis. The measured spectra were accurately analyzed by HYPERMET-PC. Prompt -ray energies and associated -ray production cross-sections have been determined by internal standardization. The resulting catalog contains prompt -ray data from neutron capture and other reactions such as (n,), and decay -ray data from short-lived reaction products. Data have been measured for nearly all stable elements, from hydrogen to uranium. Generally, data for several isotopes are given, to enable isotopic analysis as well. The whole library, including elemental spectra, will be available as a book.     

Recent developments in HYPERMET PC

HYPERMET PC is a user-friendly -ray spectrum analysis software package developed at Budapest, mainly for the purpose of prompt- neutron activation analysis (PGAA). The peak fitting algorithm is an improved version of the well-known HYPERMET code, and contains a partial peak-parameter calibration to describe peak shapes more accurately in the wide energy range typical for prompt- spectra. A nuclide identification routine has also been developed using a new PGAA library, shown in a parallel paper. The new module for quantitative PGAA includes all the features necessary to obtain concentration values for elements.     

Kinetics of thermal decomposition of pyrite in an inert atmosphere

The thermal decomposition of pyrite in an inert atmosphere was studied in order to obtain a detailed knowledge of the kinetics and mechanism of the reaction 2 FeS₂=2FeS+S₂, which is one of the methods of producing elementary sulphur. The process was studied under isothermal conditions at temperatures of 600, 660, 700, 750, 800 and 850 °C in a nitrogen atmosphere, by means of a thermobalance. The rate-controlling processes were determined and their kinetic parameters were calculated. The optimum temperature for the process was found to be 800 °C.

---

Zusammenfassung Es wurde die thermische Zersetzung von Pyrit in inerter Atmosphäre bestimmt, um detaillierte Informationen über Kinetik und Mechanismus der Reaktion 2 FeS₂=2FeS+S₂, einer der Darstellungsreaktionen von elementarem Schwefel zu erlangen. Der Vorgang wurde mittels einer Thermowaage unter isothermen Bedingungen bei Temperaturen von 600, 660, 700, 750, 800 und 850 °C untersucht. Es wurden die geschwindigkeitsbestimmenden Schritte bestimmt und deren kinetische Parameter errechnet. Als Optimumtemperatur für diesen Prozeß erwies sich 800 °C.

---

- 2FeS₂=2FeS + S₂, . 600, 660, 700, 750, 800 850 ° . , 800°.

     

Fast non-destructive determination of silicon in coal by means of /n,n′ γ/ and /n, γ/ processes

The possibilities were evaluated of nondestructive determination of silicon content in large-scale samples of coal /about 20–50 kg/, based on the spectrometry of prompt -radiation from processes /n, n /, E=1779 keV and /n, /, E=3539 keV and 4935 keV. The neutron sources were either²⁴¹Am–Be or²⁵²Cf located additionally in D₂O moderator. A Ge/Li/ detector was used for -radiation detection. In exposure times of up to 2 h, the detection limits of 1.3% and 0.9% and accuracies of silicon determination of 0.66% and 0.40% have been achieved in case of /n, / and /n, n / processes, respectively.     

Artifact (α, x) Reaction Gamma-Ray Peaks Reported as 241Am Decay Gamma-Rays; Comments to the Paper by Abdulrahman Abdul-Hadi, J. Radioanal. Nucl. Chem., 231 (1998) 147

Review of a recent paper reporting the -ray energies and intensities associated with the decay of ²⁴¹Am has resulted in the conclusion that some of the rays were misidentified. The misidentified -rays are not associated with the decay of ²⁴¹Am, but rather are prompt -rays from alpha-induced reactions.     

Synthesis of γ- dihydropyrones and β- dihydrofuranones on the basis of acetylenic γ- and δ-keto alcohols and acetals of γ- and δ-formyl alcohols

Acetylenic - and -keto alcohols and acetals of acetylenic - and -keto alcohols and acetals of acetylenic - and -formyl alcohols undergo cyclization to -dihydropyrones and -dihydrofuranones under the influence of acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1471–1473, November, 1976.     

High precision determination of uranium in ore by gamma-ray spectrometry

A new approach for the determination of elemental uranium in uranium bearing ore, using high resolution -ray spectrometry, was applied. Using a variant of the enrichment technique an agreement of better than 1% has been obtained between -ray measurement results and a certified value obtained by other analytical methods. For the calibration of the -ray spectrometer uranium reference samples have been used which are made available jointly in Europe and the USA as Certified Reference Materials for Gamma-Ray Spectrometry (EC NRM 171 and NBS SRM 969, respectively). The measured ore has been put in a special designed container which ensured in all directions seen from the radiation window an uniform degree of infinite thickness of about 95%. The results can be taken as an example for the applicability of -ray spectrometry when high accuracy is required and under conditions were homogeneously distributed elemental uranium is embedded in larger amount of matrix material.     

A new improved expression for gamma-ray detection efficiency of Ge(Li) detectors

In the present paper, a new improved expression for -ray detection efficiency of Ge(Li) detectors, ⁰ , is given. It is represented as a continuous function of x (viz. E ^–1) with a maximum and decreases very rapidly to a small positive value as -ray energy, E, drops to 40 keV or lower, but slowly as E rises to 1.7 MeV or higher. Since it can well represent the whole physical process of the -ray detection, this expression may be one of the simplest and most precise representations, for ⁰ at the present time.     

Ceramic glaze analysis by simultaneous in-beam PGAA and XRFS

Twenty-one ready-to-use hobby glazes, of which 18 were labeled safe for food containers (SFFC), were analyzed for Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Gd, Hf, K, Mn, Na, Pb, Si, Sm, Sr, Ti, Zn, and Zr by neutron capture prompt -ray activation analysis (PGAA). Simultaneously, Pb was also determined by X-ray fluorescence spectrometry (XRFS) using Pb K X-rays induced by the -ray component of the neutron beam. The XRFS limits of detection were 200–400 g Pb·g^–1 (dry weight), a factor of 100 better than those for PGAA. Pb concentrations (by dry weight; with weight losses ranging from 28 to 49% after air-drying) found were 0.16–27.2% in the SFFC glazes and 0.86–32% in the other glazes. The SFFC glazes contained from <0.6 to 202 g Cd·g^–1, and Co, Cr, and Cu (elements which may enhance Pb leaching from fired glazes) were found in concentrations up to 1.2, 2.7, and 5.6%, respectively. Method accuracy was demonstrated with the analysis of soil, fly ash, and glass standard reference materials.     

188Os Low Excited Levels

The -ray spectra of ¹⁸⁸Re decay have been studied by using a compton-suppressed spectrometer and a three parameters --T list coincidence system. Six -rays at 557, 810, 1463, 1867, 1936 and 2022 keV and three levels at 1443, 1936 and 2022 keV are confirmed again. Eight new -rays at 309.60±0.04, 826.90±0.02, 979.29±0.08, 1086.13±0.03, 1103.7±0.4, 1828.2±0.1, 1842.5±0.2, 1982.5±0.2 keV have been identified, three new levels at 309.60, 1828.2 and 1982.5 keV are assigned. The ^–-decay branching ratio is deduced.     

Effect of water on the desorption of carbon dioxide from the surface of alumina

Based on investigations of temperature-programmed desorption of CO₂ from -Al₂O₃ surface, three forms of CO₂ adsorption differing considerably in quantitative contributions and temperature ranges of desorption have been distinguished. A significant inhibiting influence of water on CO₂ adsorption has been observed. Water adsorption results in gradual blocking of high and medium-energy adsorptive centers of CO₂ on -Al₂O₃.

---

- CO₂ -Al₂O₃ CO₂, . CO₂. CO₂ Al₂O₃ .

     

Studies of trace element transport in plants using high resolution γ-ray spectroscopy and perturbed directional correlation measurements

Two examples are given to illustrate how modern experimental techniques may extend the scope of possibilities of radiotracer applications. The first example refers to the use of a Ge-detector -ray spectrometer to measure the transport in plants of 15 elements simultaneously. The second example presented is an in-vivo study of the binding of Cd-ions in plants using meansurements of perturbed --directional correlations.     

Cold neutron prompt gamma-ray activation analysis at NIST — Recent developments

The cold neutron capture prompt -ray activation analysis (CNPGAA) spectrometer located in the Cold Neutron Research Facility (CNRF) at NIST has proven useful for the analysis of hydrogen and other elements in a wide variety of materials. Modifications of the instrument and the CNRF have resulted in improved measurement capabilities for PGAA. The addition of an atmosphere-controlled sample chamber and Compton suppression have reduced -ray background and increased signal-to-noise ratio. More recent revisions are expected to yield still further improvement in analytical capabilities. Replacement of the D₂O ice cold source with a liquid H₂ moderator is expected to yield a 5–10 fold increase in neutron capture rate, and improved neutron and -ray shielding will result in further reduction of the background. Other modifications to the instrument allow easier sample mounting and more precise positioning of samples in the neutron beam. Significant improvements in detection limits and analytical accuracy are expected.     

Synthesis of two regiospecific isomers of monotosyl-γ-cyclodextrin

Tosylation of -cyclodextrin in an aqueous alkaline solution gave two regiospecific isomers (2-monotosyl--cyclodextrin(1) and 6-monotosyl--cyclodextrin(2)), that could recognize and catalyze small sized guest molecules; 2-monotosyl--CD recognized small sized guest molecules more effectively than did 6-monotosyl--CD.     

Gamma-ray pulse height spectrum of241Am-Be source by ‘Li-BC501 (n-γ) spectrometer system

Neutrons from a source are moderated by means of hydrogenous materials such as polyethylene (PE) or water to reduce the energy of fast neutrons and to increase the fluence rate of moderated neutrons. The rise-time and -ray pulse height spectrum from a PE moderated²⁴¹Am-Be neutron-gamma (n-) mixed source were measured by using⁶Li-BC501 scintillation detector and pulse shape discriminator (PSD) system. The difference in rise-time between and neutron signals tumed out to be 18.5 ns for the⁶Li-BC501 (n-) spectrometer system. The figure of merit (FOM) for this separation was estimated to be 1.52, and this was compared with the published results. From this comparison, the⁶Li-BC501 system has much superior characteristics in (n-) separation to other detector systems. Two Compton edges at around 1.87 and 3.99 MeV which are produced by H(n,)D reaction and by the first excited state of¹²C^* from Be(, n)¹²C^* reaction were also investigated.     

A digital photopeak integration in activation analysis

A study of the precision attainable by two methods of -ray photopeak computation has been carried out. The total peak area method (TPA) and the proposed new method have been compared. The method offered is digital and simulates repeatedly accumulations of -ray spectra. The method described here computes the apparent net peak area without a clear distinction between peak and non-peak related channels. The proposed method is considered to be the most advantageous because of its relatively high precision.     

Decay of 1.643-hr 95Ru to 95Tc

The decay of ⁹⁵Ru has been investigated by means of -ray spectroscopy. The ⁹⁵Ru nuclei were produced by the reaction ⁹²Mo(,n)⁹⁵Ru at the beam energy of 17 MeV. High-purity Ge detectors have been used singly and in coincidence to study -rays in the decay of ⁹⁵Ru to ⁹⁵Tc. 132 -rays are reported, among them, energies and intensities for 127 transitions have been determined. A decay scheme of ⁹⁵Ru with 31 levels is proposed which accommodates 127 of these transitions. Spins and parities for three new levels are proposed from calculated logft values, measured -ray branching ratios, and in-beam experiment results of the daughter nucleus ⁹⁵Tc.     

Determination of attenuation coefficient for self-absorption correction in routine gamma ray spectrometry of environmental bulk sample

A simple method to determine -ray attenuation coefficients using Ba-133 -rays has been developed and applied to self-absorption correction in routine -ray spectrometry for environmental samples composed of unknown matrix elements. Experimental values of the mass attenuation coefficient obtained by the method agree well with calculated values for samples of known elemental composition which was determined by means of chemical analysis.     

Zur gruppentheoretischen Bestimmung der Atomzustände in Ligandenfeldern

Zusammenfassung Es wird vorgeschlagen, die Bezeichnungen weak-field-Methode bzw. strong-field-Methode durch (L)-Methode bzw. ()-Methode zu ersetzen.Nach einer kurzen Einführung in die ()-Methode wird mit den Mitteln der Gruppen-und Darstellungstheorie eine Formel abgeleitet, mit deren Hilfe man schnell Rasse und Multiplizität der Terme eines Komplexions in der ()-Methode angeben kann. Einige Spezialfälle dieser Formel und die systematische Bestimmung der ()-Funktionen werden erörtert.

---

It is suggested that the misleading designations weak field method and strong field method be replaced by (L) method and () method, respectively.Following a brief introduction to the () method an equation is derived by group theoretical means which leads to rapid classification of the () terms. Several special cases and short cuts are discussed as well as the systematic determination of the () functions.

---

Résumé Le remplacement des termes «méthode du champ faible» et «méthode du champ fort» par «méthode (L)» et «méthode ()» est proposé.Après une introduction dans la méthode () une formule est dérivée à l'aide de la théorie des groupes et des représentations, qui donne la représentation irréductible et la multiplicité des termes d'un ion complexe dans le cadre de la méthode (). Quelques cas spéciaux de cette formule et la détermination systématique des fonctions (/gG) sont discutés.

---

---

Ich danke Herrn Professor Dr. H. Hartmann für den Hinweis auf das vorliegende Problem und der Deutsehen Forschungsgemeinschaft für ein Stipendium.     

Studies with a derivatograph of the properties of a water film on a marble surface modified by tetradecylammonium chloride (TDACl)

The properties of water layers on bare marble and on marble samples covered with various amounts of tetradecylammonium chloride (TDACl) after flotation were investigated by thermal analysis methods. The dependences of the layer thickness, activation energy, enthalpy and entropy of the bonded watervs. the amount of TDACl previously deposited on the marble surface were determined. The results obtained and the literature data were used to propose an interpretation of the changes caused in these parameters by the coverage of the marble surface with TDACl molecules. A correlation between these parameters and the changes in water structure and marble flotatibility is also presented.

---

Zusammenfassung Eigenschaften von Wasserfilmen auf unbeschichteten und mit Tetradecylammoniumchlorid (TDACl) in unterschiedlichen Mengen bedeckten Marmorproben wurden nach Flotation thermoanalytisch untersucht. Die Abhängigkeit der Schichtdicke, der Aktivierungsenergie und der Enthalpie und Entropie des gebundenen Wassers von der Menge des vorhergehend auf die Marmoroberfläche aufgebrachten TDACl wurden ermittelt. Die durch die Bedeckung der Marmoroberfläche mit TDACl verursachten Veränderungen dieser Parameter werden anhand der erhaltenen Resultate und von Literaturangaben interpretiert. Beziehungen zwischen diesen Parameters und Veränderungen der Wasserstrukturen und der Flotierbarkeit des Marmors werden angegeben.

---

, (). , , . , , , . , .