The average number of neutrons νeff emitted by the isotopes U233, U235 and Pu239 on capture of neutrons with energies from 30 to 900 key

Measurements are taken on _eff for the isotopes U²³³, U²³⁵ and Pu²³⁹ for neutrons with energies from 30 to 900 kev. It is discovered that in this energy region _eff increases substantially as the neutron energy increases.Part of the results of this work have been communicated at discussions at the Geneva Conference on the Peaceful Uses of Atomic Energy in August, 1955.The authors take this opportunity to express their gratitude to Academician L V. Kurchatov, under whose initiative the experiments devoted to the study of the dependence of _eff on neutron energy were conducted.     

Investigation of Hydrogen Alloys by Positron Annihilation and PAC

In the present work two hydrogen storage alloys Pd0.75Ag0.25 and LaNi4.25Al0.75 are studied by the positron annihilation and perturbed angular correlation techniques.     

Investigation of Hydrogen Alloys by Positron Annihilation and PAC

In the present work two hydrogen storage alloys Pd0.75Ag0.25 and LaNi4.25Al0.75 are studied by the positron annihilation and perturbed angular correlation techniques. The Pd0.75Ag0.25Hx alloys with a hydrogen concentration ranging from 0 to 0.35 are inves…     

Measurements of neutron spectra from iron and boron-in-polyethylene bombarded with 14 MeV neutrons

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Compatibility Investigation of PdAg Alloy With Hydrogen by Positron Annihilation

PdAg alloy is a potential energy storage material and important deuterium and tritium technology material. The microstructure of PdAgHx with a hydrogen concentration x ranging from 0 to 0.35 has been investigated systematically by positron annihilation li…     

Investigation of trace elements in Guangxi ancient pottery by INAA

Guangxi Zhuang Nationality Autonomous Region is an original place for manufacture of ancient pottery in China since Zenpiyan site.dated 9240-10370 years ago,was excavated.Contents of trace elements La,Ce,Nd,Sm,Eu,Tb,Yb,Lu,U,Th,Sc,Ta,Ba,Cs,Rb,Sr and Zr in 44 porttery shards from Guangxi sites,dated from 1450B.C. to 200A.D.,were dtermined by INAA and XRF.The proveniences of the 44 samples are postulated by the analyses of geochemical parameters.     

Investigation of Divertor Detachment in EAST by ＇Two-Point＇ Model

Divertor plasma detachment offers one of the most promising operating modes for fusion devices because of low target power loading. In this article a ＇two-point＇ model is used to investigate the formation of detachment and explore the route to detachment in EAST, in order to find an ideal operation window. The simulation results show that impurity radiation and ionneutral friction are the main causes of divertor plasma detachment at the target plates. Raising the safety factor and reducing the upstream power density provide effective means to achieve the detachment due to the increased radiation power fraction. Puffing Ar and Ne impurities and raising the safety factor can bring the upstream high plasma temperature region （above 100 eV） and the low target plasma temperature region （below 10 eV） close to each other in terms of the separatrix density. But it is difficult to find a common operating region which satisfies both conditions. High recycling and detached regimes provides an ideal operation window because of the steady upstream condition and low target power load.     

Determination of energy absorption in a mixed flux of fast neutrons and γ-rays by an ionization method

The possibility of separate determinations of the energy absorption of fast neutrons and -rays in the mixed radiation flux from a reactor has been studied with ioni/ation chambers. Three chambers with different hydrogenous fillers were used: polyethylene with an ethylene filler; graphite with a CO₂ filler and a chamber made from aerion, a conducting plastic, which was filled with a mixture of ethylene and CO₂. Calculations have been carried out to ascertain the sensitivity of these chambers to neutrons with energies ranging from 0.2–8 Mev. Variation of the neutron spectrum over wide limits has no effect on the accuracy in the determination of the absorbed dose in the hydrogenous substrates. A calculation shows that the error in the determination of the absorbed energy for fast neutrons is approximately 15% and is a weak function of the relative doses of neutrons and -rays.In conclusion the authors wish to express their gratitude to Yu. F. Chernilin for help in this experiment and T. B. Radzievskii for discussion of the results.     

Effect of hydrogen on SiC-C films with AES and XPS analyses

SiC-C films with different content of SiC were deposited with r. f. magnetron sputtering followed by argon ion bombardment. These films were then permeated by hydrogen gas under the pressure of 3.23 × 107 Pa for 3h at 500K. AES and XPS were used to analyze chemical bonding states of C and Si in the SiC-C films as well as contaminating oxygen before and after hydrogen gas permeation in order to study the effect of hydrogen on them. Related mechanism was discussed in this paper.     

Investigation of the γ-rays accompanying thermal-neutron capture by certain rare-earth nuclei

Using a scintillation spectrometer measurements have been made of the spectra of -rays accompanying thermal-neutron capture in a number of nuclei.A number of intense lines have been found below 300 kev in the -ray spectra for thermal-neutron capture in europium, gadolinium, dysprosium, holmium, erbium, thulium, hafnium and tantalum. Lines corresponding to 4⁺2⁺ and 2⁺0⁺ transitions between rotational levels'of Er¹⁶⁸ and Hf¹⁷⁸ were found in the erbium and hafnium spectra. The intensity of these transitions corresponds to 0.5–0.8 photons per capture event.The authors are indebted to Academician I. V. Kurchatov for his interest in the work and to Professor L. V. Groshev, V. M. Strutinskii and D. P. Grechukhin for a number of valuable comments and Professor I. A. Zaozerskii for kindly furnishing the rare-earth samples.We wish to express our gratitude to G. P. Mel'nikov for providing reliable operation of the electronic apparatus.     

Investigation of properties of μ-mesic atoms and μ-mesic molecules of hydrogen and deuterium at the Dubna 680-MeV synchrocyclotron

Summary While the problem of hydrogen -mesic atoms was first probed into theoretically as far back as about 15 years ago, the intensification of experimental research on this topic does not date back past the recent half-decade, for practical purposes. At the same time, we find this to be one of the most vigorously developing new fields in muon physics in the recent period. One brilliant piece of evidence in support of this view is, for instance, the fact that while only two or three experimental papers, including the well-known paper by L. Alvarez and colleagues reporting the detection of -catalysis, were available in the literature at the start of our experiments on hydrogen mesic atoms at the Dubna synchrocyclotron facilities, at the present time research on various aspects of this very problem is under way at virtually all the large synchrocyclotrons throughout the world. It may be seen that, as a result of those experiments performed at Dubna, the principal characteristics of the most important mesoatomic processes occurring in hydrogen and deuterium have been determined quantitatively; a number of phenomena are being studied first (e. g., scattering of p-mesoatoms on protons). The values found for the probabilities of a -meson jumping to deuterium, of formation of the mesic molecule pp, and jumping to complex nuclei, are in excellent accord with calculations, and provide confirmation of the correctness of the mechanisms invoked in theoretical treatments to explain the processes. Disagreement has cropped up in some instances between empirical results and data derived from theoretical analysis (the larger experimental value of _dd), and the results of measurements performed in different laboratories have been at variance in some cases. This is entirely to be expected in the study of new phenomena. However, there is every reason for assuming that the further development of experiment and theory will make it possible to overcome these difficulties, to probe still deeper into the secrets of the world of mesic atoms, and to reveal new characteristic properties and regularities in this peculiar state of matter.Translated from Atomnaya Énergiya, Vol. 14, No. 1, pp. 27–37, January, 1963     

γ-ray spectra from the radiation capture of neutrons for even-even radiating nuclei with rotational levels

Using a magnetic Compton spectrometer, we measured the spectra of the -rays arising from the capture of thermal neutrons by nuclei of gadolinium, erbium, hafnium, dysprosium and tantalum in the energy range 0.3–9 Mev. We determined the energies and the intensities of the -lines. For the first three elements, the radiating nuclei are the even-even nuclei₆₄Gd ₉₂ ¹⁵⁶ ,₆₄Gd ₉₄ ¹⁵⁸ ,₆₈Er ₁₀₀ ¹⁶⁸ and₇₂Hf ₁₀₆ ¹⁷⁸ , which have rotational structural levels close to the ground state. The peculiarity of the spectra of these nuclei is the presence of a group of closely placed intense -lines with energies of 1 Mev. These lines are absent in the case of even-odd (for example,₆₆Dy ₉₉ ¹⁶⁵ ) and odd-odd radiating nuclei (for example,₇₃Ta₁₀₉ ¹⁸²). The peculiarities of the -ray spectra noted are due to the structure of the lower nuclear levels.