Defect formation energy for charge states of CdMnTe

International Nuclear Information System (INIS)

Mehrabova, M.A.; Orujov, H.S.; Hasanli, R.N.

2014-01-01

Full text : Cd 1 -xMn x Te semimagnetic semiconductors are promising materials for X-ray and gamma-detectors, solar cells, optic insulators and etc. For obtaining high-sensitive and radiation-resistant materials, as well as creation of devices based on them it is necessary to know the mechanism of defect formation in semimagnetic conductors. Defects in semiconductors not only influence on electrical and optic properties of these materials, but also display their interesting physical properties

Optically detected electron spin-flip resonance in CdMnTe

International Nuclear Information System (INIS)

Zeng, S.; Smith, L.C.; Davies, J.J.; Wolverson, D.; Bingham, S.J.; Aliev, G.N.

2006-01-01

We show that the spin-flip of electrons at neutral donors in a dilute magnetic semiconductor can be observed directly by means of optically-detected magnetic resonance (ODMR). Spectra obtained at 105 GHz for a bulk crystal of Cd 1-x Mn x Te with x = 0.005 showed strong signals with g -values ranging between 12 (at 4.2 K) and 35 (at 1.7 K), with magnetic resonance linewidths ranging from 0.3 Tesla to 0.1 Tesla at the lowest temperature. In energy terms, these linewidths are independent of temperature and agree with those in spin-flip Raman spectra from the same specimen. The line broadening is caused by fluctuations in the number of manganese ions that interact with a particular donor and an analysis of this leads to a value for the donor Bohr radius of 4.5 nm. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Spin and energy transfer between magnetic ions and free carriers in diluted-magnetic semiconductor heterostructures

Energy Technology Data Exchange (ETDEWEB)

Yakovlev, D.R. [Experimental Physics 2, University of Dortmund, 44227 Dortmund (Germany); Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Kneip, M.; Bayer, M. [Experimental Physics 2, University of Dortmund, 44227 Dortmund (Germany); Maksimov, A.A.; Tartakovskii, I.I. [Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka (Russian Federation); Keller, D.; Ossau, W.; Molenkamp, L.W. [Physikalisches Institut der Universitaet Wuerzburg, 97074 Wuerzburg (Germany); Scherbakov, A.V.; Akimov, A.V. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Waag, A. [Abteilung Halbleiterphysik, Universitaet Ulm, 89081 Ulm (Germany)

2004-03-01

In this paper we give a brief overview of our studies on dynamical processes in diluted-magnetic-semiconductor heterostructures based on (Zn,Mn)Se and (Cd,Mn)Te. Presence of free carriers is an important factor which determines the energy- and spin transfer in a coupled systems of magnetic ions, lattice (the phonon system) and carriers. We report also new data on dynamical response of magnetic ions interacting with photogenerated electron-hole plasma. (Zn,Mn)Se/(Zn,Be)Se structures with relatively high Mn content of 11% provide spin-lattice relaxation time of about 20 ns, which is considerably shorter then the characteristic times of nonequilibrium phonons ranging to 1 {mu}s. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Influence of gamma-radiation on electrophysical properties of CdMnTe

International Nuclear Information System (INIS)

Mehrabova, M.A.; Taghiyev, T.B.; Huseynov, N.I.; Nuriyev, H.R.; Nazarov, A.M.; Sadigov, R.M.

2014-01-01

Full text : Cd 1 -xMn x Te thin films were obtained on mica substrates at source temperatures T=850 degrees Celsius and substrate temperature T=300during 10 min and 15 min respectively. The results of X-ray diffraction measurements showed that the crystals had a periodical structure, as designed artificially. It has been found that the synthesized samples and films obtained on mica substrates have a polycrystalline structure and indicated on the base of cubic lattice with appropriate parameters

First-principles calculations of the magnetic properties of (Cd,Mn)Te nanocrystals

Science.gov (United States)

Echeverría-Arrondo, C.; Pérez-Conde, J.; Ayuela, A.

2009-04-01

We investigate the electronic and magnetic properties of Mn-doped CdTe nanocrystals (NCs) with ˜2nm in diameter which can be experimentally synthesized with Mn atoms inside. Using the density-functional theory, we consider two doping cases: NCs containing one or two Mn impurities. Although the Mnd peaks carry five up electrons in the dot, the local magnetic moment on the Mn site is 4.65μB . It is smaller than 5μB because of the sp-d hybridization between the localized 3d electrons of the Mn atoms and the s - and p -type valence states of the host compound. The sp-d hybridization induces small magnetic moments on the Mn-nearest-neighbor Te sites, antiparallel to the Mn moment affecting the p -type valence states of the undoped dot, as usual for a kinetic-mediated exchange magnetic coupling. Furthermore, we calculate the parameters standing for the sp-d exchange interactions. Conduction N0α and valence N0β are close to the experimental bulk values when the Mn impurities occupy bulklike NCs’ central positions, and they tend to zero close to the surface. This behavior is further explained by an analysis of valence-band-edge states showing that symmetry breaking splits the states and in consequence reduces the exchange. For two Mn atoms in several positions, the valence edge states show a further departure from an interpretation based in a perturbative treatment. We also calculate the d-d exchange interactions |Jdd| between Mn spins. The largest |Jdd| value is also for Mn atoms on bulklike central sites; in comparison with the experimental d-d exchange constant in bulk Cd0.95Mn0.05Te , it is four times smaller.

Excitons in tunnel coupled CdTe and (Cd,Mn)Te quantum wells

Energy Technology Data Exchange (ETDEWEB)

Terletskii, Oleg; Ryabchenko, Sergiy; Tereshchenko, Oleksandr [Institute of Physics NASU, pr. Nauki 46, 03680 Kyiv (Ukraine); Sugakov, Volodymyr; Vertsimakha, Ganna [Institute for Nuclear Research NASU, pr. Nauki 47, 03680 Kyiv (Ukraine); Karczewski, Grzegorz [Institute of Physics PAS, Al. Lotnikow 32/46, PL-02-668 Warsaw (Poland)

2017-05-15

The photoluminescence (PL) from structures containing Cd{sub 0.95}Mn{sub 0.05}Te and CdTe quantum wells (QWs) separated by a narrow (1.94 nm) barrier was studied. The PL lines of comparable intensities from several possible exciton states were observed simultaneously at energy distances substantially exceeding kT. This means that the energy transfer in the studied systems is slower than the radiative recombination of the confined excitons. For the CdTe QW width of about 8.7-9 nm, indirect excitons with the electron and heavy hole chiefly localized in the CdTe and Cd{sub 1-x}Mn{sub x}Te QWs, respectively, were detected in the magnetic field. These indirect excitons have PL energy of about 10-20 meV above the PL line of the direct excitons in the CdTe QW. The observation of the PL from the indirect excitons which are not the lowest excitations in the structure is a distinctive feature of the system. Photoluminescence intensity dependence on the energy and the magnetic field. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Anisotropic exchange interaction induced by a single photon in semiconductor microcavities

Science.gov (United States)

Chiappe, G.; Fernández-Rossier, J.; Louis, E.; Anda, E. V.

2005-12-01

We investigate coupling of localized spins in a semiconductor quantum dot embedded in a microcavity. The lowest cavity mode and the quantum dot exciton are coupled and close in energy, forming a polariton. The fermions forming the exciton interact with localized spins via exchange. Exact diagonalization of a Hamiltonian in which photons, spins, and excitons are treated quantum mechanically shows that a single polariton induces a sizable indirect anisotropic exchange interaction between spins. At sufficiently low temperatures strong ferromagnetic correlations show up without an appreciable increase in exciton population. In the case of a (Cd,Mn)Te quantum dot, Mn-Mn ferromagnetic coupling is still significant at 1 K : spin-spin correlation around 3 for exciton occupation smaller than 0.3. We find that the interaction mediated by photon-polaritons is 10 times stronger than the one induced by a classical field for equal Rabi splitting.

Quantitative measurements of magnetic polaron binding on acceptors in CdMnTe alloys

Science.gov (United States)

Nhung, Tran Hong; Planel, R.

1983-03-01

The acceptor binding energy is measured as a function of Temperature and composition in Cd1-x Mnx Te alloys, by time resolved spectroscopy. The Bound magnetic polaron effect is measured and compared with a theory accouting for magnetic saturation and fluctuations.

Synthesis of dilute magnetic semiconductors by ion implantation

International Nuclear Information System (INIS)

Braunstein, G.H.; Dresselhaus, G.; Withrow, S.P.

1986-01-01

We have synthesized layers of CdMnTe by implantation of Mn into CdTe. Samples of CdTe have been implanted with Mn ions of 60 keV energy to fluences in the range 1 x 10 13 cm -2 to 2 x 10 16 cm -2 resulting in local concentrations of up to 10% at the maximum of the Mn distribution. Rutherford backscattering-channeling analysis has been used to study the radiation damage after implantation and after subsequent rapid thermal annealing (RTA). These experiments reveal that RTA for 15 sec at a temperature T greater than or equal to 700 0 C results in the complete recovery of the lattice order, without affecting the stoichiometry of CdTe. Photoluminescence (PL) measurements of a sample showing complete annealing reveal an increase in the band gap corresponding to the synthesis of very dilute (x approx. = 0.004) Cd/sub 1-x/Mn/sub x/Te. A shift of the excitonic PL peak to lower energies is observed when a magnetic field H less than or equal to 1T is applied. These measurements provide clear evidence for the synthesis of a DMS by ion implantation of Mn into CdTe

Ba2NiOsO6 : A Dirac-Mott insulator with ferromagnetism near 100 K

International Nuclear Information System (INIS)

Feng, Hai L.; Calder, Stuart

2016-01-01

In this study, the ferromagnetic semiconductor Ba 2 NiOsO 6 (T mag ~ 100 K) was synthesized at 6 GPa and 1500 °C. It crystallizes into a double perovskite structure [Fm - 3m; a = 8.0428 (1) Å], where the Ni 2+ and Os 6+ ions are perfectly ordered at the perovskite B site. We show that the spin-orbit coupling of Os 6+ plays an essential role in opening the charge gap. The magnetic state was investigated by density functional theory calculations and powder neutron diffraction. The latter revealed a collinear ferromagnetic order in a > 21 kOe magnetic field at 5 K. The ferromagnetic gapped state is fundamentally different from that of known dilute magnetic semiconductors such as (Ga,Mn)As and (Cd,Mn)Te (T mag < 180 K), the spin-gapless semiconductor Mn 2 CoAl (T mag ~ 720 K), and the ferromagnetic insulators EuO (T mag ~ 70 K) and Bi 3 Cr 3 O 11 (T mag ~ 220 K). It is also qualitatively different from known ferrimagnetic insulators and semiconductors, which are characterized by an antiparallel spin arrangement. Our finding of the ferromagnetic semiconductivity of Ba 2 NiOsO 6 should increase interest in the platinum group oxides, because this alternative class of materials should be useful in the development of spintronic, quantum magnetic, and related devices.

Development and test of a high-resolution detector for synchrotron radiation imaging; Entwicklung und Test eines hochaufloesenden Detektors zur Bildgebung mit Synchrotronstrahlung

Energy Technology Data Exchange (ETDEWEB)

Ruebsamen, Oliver

2011-07-01

For medical imaging with x-rays, especially coronary angiography in vivo, high position resolution detectors are needed, thereby being able to deliver a contrast better than 1% and a readout speed faster than milliseconds. Since coronary angiography uses a contrast agent like iodine or gadolinium, high energy photons up to 51 keV are needed for imaging. The k-edge subtraction method allows visualizing small vessels because of the sharp jump of absorption at the k-edge of the contrast agent and the almost constant absorption of the surrounding tissue and bone, as well as the measurement of the concentration of the contrast agent to explore heart dynamics. Various detectors and detector materials are in use or development to match these conditions. Solid state Si-, Ge-, CdZnTe-, CdMnTe- or CdTe-seminconductor detectors are used or tested for imaging, each of them having different physical and/or technical problems which prevent to meet the required specifications. These problems are low absorption efficiency (Si) and reduced position resolution if scintillators are used, cooling and poor resolution (Ge) and charge spread along many pixels and technical problems to manufacture a detector chip (CdZnTe, CdMnTe, CdTe). The approach made in this work is a gas filled ionization chamber, built as a integrating line detector. In general, ionization chambers always suffer from poor absorption efficiency, but this can be overcome using the noble Gases Ar, Kr or Xe at very high gas pressures around 50 bar and relatively long (in the range of cm) anode strips. This design is critical for parallax effects, so an x-ray beam with a very small beam divergence is needed. This requirement in combination with the desired contrast and timing resolution can only be achieved by synchrotron light sources of the third generation, like the DORIS ring at DESY, Hamburg or the ESR in Grenoble. A different problem of ionization chambers is fluorescence photons, which produce a background signal

Research on the Primary Processes of Radiation-Initiated Polymerization; Recherches sur les processus primaires de polymerisation amorcee par rayonnements; Issledovaniya osnovnykh protsessov polimerizatsii pod vozdejstviem oblucheniya; Estudios sobre los procesos primarios en la polimerizacion radioinducida

Energy Technology Data Exchange (ETDEWEB)

Okamura, S; Manabe, T; Higashimura, T; Oishi, Y; Futami, S

1960-07-15

Excitation energy transfer in benzene solutions of monomers, polymers and copolymers has been studied by observations on the quenching of terphenyl fluorescence produced by gamma radiation. The ease of energy transfer from benzene to various monomers is conjugated monomers > unconjugated > monomers > corresponding saturated compounds. Quenching experiments were also carried out using polymer solutions in benzene. The order of efficiencies was crepe rubber > polystyrene > polyvinyl acetate > acrylic polymers. The results obtained for quenching by a styrene-methyl methacrylate copolymer indicated that the specific quenching efficiency of the styrene units in the copolymer was less than in the homopolymer. The gamma ray initiated polymerisation of styrene in methylene dichloride solutions at low temperature was studied. The results obtained for the dependence of polymerisation rate on intensity are consistent with an ionic mechanism. The composition of the copolymer obtained with methyl methacrylate also supports this view. (author) [French] Les auteurs ont etudie la transmission de l'energie d'excitation dans les solutions de benzene du fait de la presence de monomeres, polymeres et copolymeres, en etudiant l'extinction de la fluorescence du terphenyle induite par rayons gamma. On peut classer les divers monomeres en trois categories selon l'ordre de facilite avec laquelle l'energie du benzene leur est transmise : monomeres conjugues, monomeres non conjugues, composes satures correspondants. Les auteurs ont egalement fait des experiences sur des polymeres dans une solution de benzene. L'efficacite va en decroissant dans l'ordre suivant: caoutchouc naturel, polystyrolene, acetate de polyvinyle, polymere acrylique. Les resultats obtenus pour le copolymere styrolene-methacrylate de methyle montrent que l'efficacite d'extinction du styrolene est plus faible dans le cas des copolymeres que dans le cas des homopolymeres. Les auteurs ont etudie la polymerisation du styrolene amorcee au moyen de rayons gamma dans une solution de dichlorure de methylene a basse temperature. Le rapport direct constate entre la vitesse de polymerisation et l'intensite repond a une caracteristique du mecanisme de polymerisation ionique. La composition du copolymere obtenu avec le methacrylate de methyle vient egalement a l'appui de cette hypothese. (author) [Spanish] Observando la extincion de la luminiscencia del terienilo inducida por los rayos gamma, se ha estudiado el proceso de transmision de la energia de excitacion en soluciones bencenicas de monomeros, polimeros y copolimeros. La facilidad con que la energia se transmite del benceno a los diversos monomeros responde al siguiente orden decreciente: monomeros conjugados > monomeros no conjugados > compuestos saturados correspondientes. Tambien se realizaron experimentos sobre la extincion de la luminiscencia utilizando polimeros disueltos en benceno. El poder de extincion de los polimeros disminuye con arreglo al siguiente orden: caucho natural > poliestireno > acetato de polivinilo > polimeros acrilicos. Los resultados obtenidos al emplear un copolimero de estireno-metacrilato de metilo indicaron que el poder extintor especifico de los grupos estireno del copolimero es inferior al observado en el caso del homopolimero. La polimerizacion inducida por rayos gamma del estireno disuelto en diclorometileno tambien se estudio a bajas temperaturas. Los resultados obtenidos en lo que se refiere a la relacion existente entre la velocidad de polimerizacion y la intensidad de irradiacion parecen indicar que el mecanismo es de naturaleza ionica. La composicion del copolimero obtenido a partir de metacrilato de metilo tambien corrobora esta opinion. (author) [Russian] Peredacha ehnergii vozbuzhdeniya v benzol'nykh rastvorakh monomerov, polimerov i sopolimerov izuchayutsya putem nablyudeniya kvenchinga trifinil'noj fluorestsentsii, poluchaemogo v rezul'tate gamma-oblucheniya. Sposobnost' peredachi ehnergii ot benzola razlichnym monomeram sleduyushchaya : sopryazhennye monomery > nesopryazhennye monomery > sootvetstvuyushchie predel'nye soedineniya. EHksperimenty s kvenchingom provodyatsya takzhe s ispol'zovaniem rastvorov polimerov v benzole. Poryadok otdachi sleduyushchij : natural'nyj kauchuk > polistirol > polivinilovaya sol' > akrilovye polimery. Rezul'taty, poluchennye dlya kvenchinga s pomoshch'yu sopolimera stirol-metil-metakrilata, ukazyvayut na to, chto osobaya sposobnost' k kvenchingu soedinenij stirola v sopolimere proyavlyaetsya v men'shej stepeni, chem v gomopolimere . Issledovalas' polimerizatsiya stirola v rastvorakh dvukhloristogo metilena pri nizkoj temperature. Poluchennye rezul'taty otnositel'no zavisimosti skorosti polimerizatsii ot intensivnosti soglasuyutsya s ionnym mekhanizmom. Sostav sopolimerov, poluchennykh s metil-metakrilatom, takzhe podtverzhdaet ehtot vyvod. (author)

Halogen doping of II-VI semiconductors during molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Waag, A.; Litz, Th.; Fischer, F.; Heinke, H.; Scholl, S.; Hommel, D.; Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstoff-Forschung, Stuttgart (Germany))

1994-04-14

Results on the halogen doping of CdTe, (CdMn)Te as well as (CdMg)Te thin films and quantum well structures are reported. The structures were grown by molecular beam epitaxy. The samples have been investigated by Van der Pauw, photoconductivity, X-ray diffraction, XPS and SIMS measurements. ZnCl[sub 2] and ZnBr[sub 2] have been used as dopant sources. Free carrier concentrations at room temperature above 10[sup 18] cm[sup -3] can easily be achieved for CdTe for a wide range of Cd/Te flux ratios and substrate temperatures. In the ternary alloys, the free carrier concentration decreases drastically with increasing x-values, despite a constant incorporation of the dopant species. In addition, persistent photoconductivity has been observed in n-type doped ternary thin films at low temperatures. The decrease of the free carrier concentration with x-value is common to other wide-gap ternary alloys, and the reason for it is discussed in the frame of DX-like deep donor impurities in ternary II-VI compounds. In first experiments on planar halogen doping of CdTe, a doping level of 5x10[sup 18] cm[sup -3] could be reached in the doped regions, the highest value ever reported for CdTe. A clear influence of dopant incorporation on the structural quality of CdTe thin films has been seen even for dopant concentrations of as low as 10[sup 18] cm[sup -3]. The FWHM of the rocking curves decreased by a factor of 2 with increasing dopant incorporation. SIMS as well as XPS measurements demonstrate that the Cl/Zn and Br/Zn ratio in the doped films is 2/1, but no chemical shift corresponding to Zn-Cl or Zn-Br bonds could be detected. A model for the incorporation of the halogens is proposed on the basis of these results

Synthesis of Graft Copolymers by Small Doses of Irradiation; Synthese des copolymeres greffes au moyen de petites doses de rayonnements; Sintez privitykh sopolimerov s pomoshch'yu malykh doz oblucheniya; Sintesis de copolimeros de injerto mediante pequenas dosis de radiacion

Energy Technology Data Exchange (ETDEWEB)

Dobo, J; Somogyi, M; Kiss, L

1960-07-15

laterales injertadas. Ello se traduce en una aceleracion, del proceso de injerto. Este efecto es especialmente pronunciado en el caso de los polimeros preformados, cuando la irradiacion es intermitente. El injerto de las moleculas de estireno puede acelerarse anadiendo algunos solventes que suprimen la accion protectora ejercida por el estireno sobre el polimero. Asimismo, el proceso puede acelerarse agregando otras sustancias. Al injertar moleculas de metacrilato de metilo en el polietileno, hemos conseguido un injerto de 6 400 por ciento con una dosis de 31 400 roentgens. Hemos examinado la estructura de los copolimeros asi obtenidos. (author) [Russian] Grafting (privivanie ) chasto soprovozhdaetsya nezhelatel'nym izmeneniem svojstv pervonachal'nogo polimera pri obluchenii monomernykh smesej polimera. Pod vozdejstviem oblucheniya grafting proiskhodit ne tol'ko v pervonachal'noj polimernoj osnove, no takzhe v bokovoj tsepi, uzhe podvergnuvshejsya graftingu. Grafting v rezul'tate ehtogo uskoryaetsya. EHtot ehffekt osobenno yarko vyrazhen v tverdykh polimerakh, esli obluchenie proizvoditsya periodicheski. Grafting stirola mozhet byt' uskoren dobavleniem nekotorykh rastvoritelej, kotorye blokiruyut zashchitnoe vozdejstvie stirola na dannyj polimer. Grafting mozhet byt' uskoren i drugimi additivami. Issleduyutsya kachestva nabukhaniya obluchennoj plenki. (author)

Chemical Changes Induced by Irradiation in Meats and Meat Components; Transformations Chimiques Provoquees par les Rayonnements dans les Viandes et Leurs Constituants; Khimicheskie prevrashcheniya v myasnykh produktakh i ikh sostavnykh chastyakh pod vozdejstviem oblucheniya; Alteraciones Quimicas Producidas por Irradiacion de las Carnes y de sus Componentes

Energy Technology Data Exchange (ETDEWEB)

Merritt, C. Jr. [Pioneering Research Division, United States Army Natick Laboratories, Natick, MA (United States)

1966-11-15

The acceptability of meats preserved by irradiation has been hampered by the formation of an irradiation flavour and odour. This flavour and odour is believed to be due to the volatile chemical compounds produced by radiation impact on the protein and lipid molecules. The analysis of the volatile compounds has been accomplished, employing programmed cryogenic temperature gas chromatography for separation of the complex mixtures obtained, and rapid scanning mass spectrometry for identification of the individually separated components. Comprehensive analyses of the volatiles from irradiated ground beef, pork, mutton, lamb, and veal, as well as the volatile irradiation degradation products of several amino acids and proteins, animal fats, methyl esters of fatty acids, and triglycerides have been made. The results of the analysis of the irradiated component meat substances are compared with those obtained from the irradiation of meat itself, and of separate meat fractions, thus establishing the contribution of each fraction to the total. Mechanisms are postulated for the formation of the volatile components from each fraction and for interactions among intermediates from different fractions. (author) [French] La comestibilite des viandes conservees par les rayonnements s'est trouvee diminuee a la suite de l'apparition dans celles-ci d'un gout et d'une odeur engendres par l'irradiation. On pense que ces derniers sont dus aux composes chimiques volatils qui sont formes par l'action des rayonnements sur les molecules des proteines et des lipides. Il a ete procede a l'analyse des composes volatils a l'aide d'un programme de chromatographie en phase gazeuse a temperature cryogenique visant a separer les constituants des melanges complexes obtenus, et par spectrometrie de masse a balayage rapide destinee a identifier les constituants separes. L'auteur a effectue des analyses completes des composes volatils emanant de viande hachee de boeuf, de porc, de mouton, d'agneau et de veau; il a egalement analyse les produits volatils de la degradation, par les rayonnements de plusieurs acides amines et proteines, de graisses animales, d'esters methyliques d'acide gras et de triglycerides. L'auteur compare les resultats de l'analyse des substances constitutives de la viande soumises a l'irradiation avec ceux obtenus par l'irradiation de la viande elle-meme et de fractions distinctes de viande, ce qui permet de determiner l'apport de chaque fraction a l'ensemble. Il postule des mecanismes expliquant la formation des elements volatils dans chacune de ces fractions ainsi que les interactions entre les sub- stances, intermediaires des differentes fractions. (author) [Spanish] El mal sabor y el mal olor originados por la irradiacion de la carne conservada son un obstaculo para su aceptacion. Se cree que este sabor y este olor desagradables se deben a.los compuestos quimicos volatiles producidos por las radiaciones en las moleculas de proteinas y lipidos. Se han analizado los compuestos volatiles por cromatografia en fase gaseosa a temperaturas sumamente bajas y con arreglo a un programa, para determinar las mezclas complejas obtenidas, y por espectrometria de masas con exploracion rapida, para identificar los componentes separados. Se han efectuado analisis minuciosos de las sustancias volatiles formadas por irradiacion en carne picada de vaca, cerdo, carnero, cordero y ternera, asi como de los productos volatiles de degradacion originados por las radiaciones en varios aminoacidos y proteinas, grasas animales, esteres metilicos de acidos grasos y trigliceridos. Los resultados del analisis de los componentes de la carne irradiados se comparan con los obtenidos irradiando la carne misma y distintas fracciones de ella. Se postulan los mecanismos de formacion de los componentes volatiles de cada fraccion y los de las interacciones de las fases intermedias correspondientes a distintas fracciones. (author) [Russian] Obluchenie razlichnyh sortov mjasa s cel'ju konservacii otrazhaetsja na vkusovyh kachestvah, vyzyvaja pojavlenie specificheskogo privkusa i zapaha. Polagajut, chto jeto ob{sup j}asnjaetsja obrazovaniem letuchih himicheskih soedinenij pri dejstvii radiacii na belki i lipidnye molekuly. Analiz letuchih soedinenij osushhestvljaetsja na gazovom hromatografe s kriogennym ohlazhdeniem do zadannoj temperatury, gde proishodit razdelenie slozhnyh smesej. Identifikacija vydelennyh komponentov provoditsja s pomoshh'ju mass-spektrometrii s bystrym skennirovaniem. Proveden ischerpyvajushhij analjz letuchih soedinenij, vydeljajushhihsja iz govjadiny, svininy, baraniny i teljatiny, kotorye byli oblucheny, a takzhe analiz letuchih soedinenij, obrazujushhihsja pri razlozhenii pod dejstviem obluchenija nekotoryh aminokislot, belkov, zhivotnogo zhira, metilovyh jefirov zhirnyh kislot i trigliceridov. Rezul'taty analizov obluchennyh komponentov mjasnyh produktov sravnivajutsja s rezul'tatami, poluchennymi pri obluchenii samogo mjasa i ego otdel'nyh frakcij, chto daet vozmozh - nost' ustanovit' rol' kazhdoj frakcii v celom. Postulirujutsja mehanizmy obrazovanija letuchih komponentov ot kazhdoj frakcii, a takzhe vzaimodejstvie promezhutochnyh produktov ot razlichnyh frakcij. (author)

Extensions of the techniques for the accelerated unspecific isotopic labelling of organic compounds; Applications nouvelles des techniques accelererees du marquage non specifique de composes organiques; Rasprostranenie metodov uskoreniya mecheniya nespetsifichnymi izotopami organicheskikh slozhnykh soedinenij; Nuevas aplicaciones de las tecnicas de marcacion inespecifica acelerada de compuestos organicos

Energy Technology Data Exchange (ETDEWEB)

Ghanem, N A [National Research Centre, El-Dokki, Cairo (Egypt); Westermark, T [Division of Physical Chemistry, Royal Institute of Technology, Stockholm 70 (Sweden)

1962-03-15

marcar, y citar ejemplos en los que este procedimiento se ha empleado con exito. Las diversas tecnicas se basan en el uso de descargas de microondas y de ondas hertzianas, descargas luminiscentes producidas por corriente continua, o alterna, o sencillamente rayos ultravioleta. Se han obtenido cantidades considerables de productos purificados con actividades superiores a 100 mcuries/g. Los tiempos de exposicion a las descargas son del orden de un minuto, y en la mayoria de los casos se observo poca descomposicion. Los autores calcularon el rendimiento energetico alcanzado en estos metodos de marcacion y lo comparan con el correspondiente a las radiaciones ionizantes empleadas por Wilzbach y otros investigadores; tambien dan los valores de G para la sustitucion isotopica. Existen pruebas de que la marcacion del poliestireno se produce en virtud de una reaccion atomo-molecula. (author) [Russian] Tsel'yu nastoyashchego doklada yavlyaetsya rassmotrenie novykh sposobov uskoreniya reaktsii mezhdu radioaktivnym gazom i materialom misheni, podlezhashchim mecheniyu, a takzhe privedenie primerov uspeshnykh sluchaev. Ehti metody vklyuchayut ispol'zovanie razryadov mikrovoln i radiovoln, tleyushchikh razryadov pod vozdejstviem istochnikov postoyannogo ili peremennogo tokov, ili prosto radiatsii ul'trafioletovykh luchej. Byla dostignuta udel'naya aktivnost', dokhodyashchaya do 100 mikrokyuri na gramm, v znachitel'nykh kolichestvakh ochishchennogo produkta. Vremya vozdejstviya razryada bylo poryadka odnoj minuty, i vo mnogikh sluchayakh razlozhenie bylo chrezvychajno ogranichennym. Dayutsya podschety ehffektivnosti ispol'zovaniya ehnergii dlya proizvodstva mecheniya ehtimi metodami po sravneniyu s zatratoj dlya toj zhe tseli ehnergii ioniziruyushchego izlucheniya, ispol'zuemoj Vil'tsbakhom i dr. ; krome togo, ukazyvayutsya znacheniya radiatsionnokhimicheskogo vykhoda G dlya zameny izotopov. Est' ukazaniya na to, chto pri mechenii polistirola mekhanizm opredelyaetsya reaktsiej atom

Linear capacity storage devices; Memoires lineaires a condensateurs; Linejnye kondensatornye nakopitel'nye ustrojstva; Dispositivos de almacenamiento de condensador, con caracteristicas lineales

Energy Technology Data Exchange (ETDEWEB)

Brovchenko, V G [Ordena Lenina Institut Atomnoj Ehnergii Imeni I.V. Kurchatova AN, SSSR (Russian Federation)

1962-04-15

nakopleniya informatsii kondensatornymi nakopitel'nymi ustrojstvami. Opisyvayutsya dve skhemy nakopitelej, rabotayushchikh linejno v bol'shom diapazone amplitud vykhodnykh signalov. V odnoj iz skhem signal oshibki izmeryaetsya differentsial'nym usilitelem. Blagodarya bol'shomu koehffitsientu usileniya usilitelya dostigaetsya vysokaya linejnost' raboty ehtogo ustrojstva. Vtoraya skhema skonstruirovana dlya raboty s impul'sami nanosekundnogo diapazona dlitel'nostej. Vkhodnye impul'sy standartnoj dlitel'nosti zapirayut pentod, v anode kotorogo raspolozhen kondensator pamyati. Tak kak zaryadka kondensatora proizvoditsya ot anodnogo pitaniya cherez generator toka, tok zaryadki ostaetsya pochti postoyannym pri izmenenii potentsiala kondensatora. Pentod imeet bol'shoe vnutrennee soprotivlenie, poehtomu posle okonchaniya vkhodnogo impul'sa tok cherez pentod pochti raven nachal'noj velichine, a zaryad, nakoplennyj kondensatorom, zapominaetsya. Dlitel'nost' pamyati informatsii ogranichena velichinami vykhodnogo soprotivleniya generatora toka i R{sub i} pentoda. Dlya uvelicheniya dlitel'nosti pamyati pered kondensatorom mozhet byt' vklyuchen diod. (author)

Assessment of End-Plug Welding of Fuel Elements; Evaluation des Soudures Terminales des Elements Combustibles; Otsenka kachestva privarki kontsevoj probki toplivnykh ehlementov; Inspeccion de la Soldadura del Tapon Terminal de los Elementos Combustibles

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Y.; Aoki, T. [Tokai Refinery, Atomic Fuel Corporation (Japan)

1965-10-15

metallicheskogo urana s aljuminievym pokrytiem. Poskol'ku v jelementah mezhdu pokrytiem i serdcevinoj sushhestvuet tol'ko mehanicheskaja svjaz', koncevaja probka mozhet ispytyvat' rastjagivajushhee naprjazhenie v rezul'tate uvelichenija obluchenija uranovoj serdceviny. Tem- peraturnye kolebanija vyzovut analogichnoe naprjazhenie v svarnyh shvah. Vsledstvie neodno- rodnosti mikrostruktury vblizi svarnyh shvov tam mozhet proizojti usilennaja korrozija pod vozdejstviem gorjachej vody. Vo vremja raboty reaktora i posle ego ostanovki neobhodimo obespechit' germetichnost'. Dlja provedenija ispytanij na prochnost' na razryv, ispytanij na polzuchest' pri vysokoj temperature, ispytanij temperaturnyh kolebanij i korrozii byli razrabotany special'- nye obrazcy. Mnogie harakteristiki svarnyh shvov byli izucheny bez razrushenija ispyty- vaemogo obrazca do provedenija ispytanij i provereny na germetichnost' v promezhutkah mezh- du ispytanijami. Jeti rezul'taty mogut byt' ispol'zovany dlja ustanovlenija standartov proverki, takih kak rentgenovskaja radiografija i vizual'naja proverka kachestva privarki koncevoj probki. Budut takzhe opisany nekotorye drugie rezul'taty, poluchennye po topliv- nym jelementam, pokrytym magnoksom ili cirkalloem. (author)

Disposal of Radioactive Wastes in Natural Salt; Elimination des Dechets Radioactifs dans le Sel Naturel; 0423 0414 ; Evacuacion de Desechos Radiactivos en Formaciones Salinas Naturales

Energy Technology Data Exchange (ETDEWEB)

Parker, F. L.; Boegly, W. J.; Bradshaw, R. L.; Empson, F. M.; Hemphill, L.; Struxness, E. G.; Tamura, T. [Health Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

1960-07-01

pueden solo estudiarse en las formaciones salinas inalteradas. En un yacimiento estratificado de sal situado en Hutchinson, Kansas, se han hecho experimentos con modelos a escala 1:5 y se estan realizando pruebas sobre el terreno a escala 1:1. (author) [Russian] Predlagaemoe ispol'zovanie polostej soljanyh zalezhej v kachestve mest dlja udalenija radioaktivnyh othodov osnovyvaetsja na: 1. Sushhestvovanii soli v techenie geologicheskih vekov, 2. Vodonepronicaemosti soli, 3. Shirokom geologicheskom rasprostranenii soli, 4. Chrezvychajno bol'shih kolichestvah imejushhejsja soli, 5. Strukturnoj prochnosti soli, 6. Sravnitel'no vysokoj teploprovodnosti soli po sravneniju s drugimi geologicheskimi obrazovanijami obshhek haraktera, 7. Vozmozhnom ispol'zovanii cennyh rasshhepljajushhihsja produktov v othodah, vvedennyh v sol', J 8. Sravnitel'no legkom sozdanii polostej v soli putem vyemki porody i eshhe bol'shej legkosti i nizkih zatratah na razrabotku v soli rastvornyh polostej, 9. Nizkoj sejsmichnosti v rajonah glavnyh soljanyh zalezhej. Zhidkie radioaktivnye othody mogut hranit'sja v polostjah, nahodjashhihsja . v zalezhah prirodnoj soli, esli strukturnye svojstva soli ne narusheny himicheskim vzaimodejstviem, davleniem, temperaturoj ili radiaciej. Analiticheskie issledovanija pokazyvajut, chto mozhno hranit' 800 gal/tonn dvuhgodichnyh othodov na 10000 MWD/T v sfere diametrom 10 futov, esli temperatura ne. prevyshaet 200 Degree-Sign po Farengejtu. Laboratornye ispytanija pokazyvajut, chto strukturnye svojstva i teploprovodnost' gornoj soli ne izmenjajutsja v znachitel'noj stepeni pod vozdejstviem vysokih doz radiacii, hotja vysokie temperatury uvelichivajut stepen' polzuchesti kak dlja obluchennyh, tak i dlja neobluchennyh obrazcov. Himicheskoe vzaimodejstvie zhidkih othodov s sol'ju daet hlor i drugie hloristye gazoobraznye soedinenija, no ih kolichestvo ne veliko. Migracija nuklidov v soli i deformacija polosti i kamery mogut byt' izucheny tol'ko v netronutoj zalezhi soli

Transmutation doping and recoil effects in semiconductors exposed to thermal neutrons; Transmutations provoquees et effets de recul dans les semi-conducteurs exposes aux neutrons thermiques; Prisadka i sdacha v rezul'tate prevrashcheniya poluprovodnikov pod dejstviem teplovykh nejtronov; Impurificacion por transmutacion y efectos de retroceso en los semiconductores expuestos a neutrones termicos

Energy Technology Data Exchange (ETDEWEB)

Crawford, Jr, J H; Cleland, J W [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN (United States)

1962-01-15

,2, 39 chasov. Poehtomu okolo 3 aktseptorov (Ca{sup 71}) vvodyatsya na kazhdyj donor (As{sup 75} i Se{sup 77}), i putem vybora prodolzhitel'nosti oblucheniya mozhno sokratit' kontsentratsiyu ehlektronov Se tipa ''n'' do ves'ma malykh znachenij ili prevratit' Se tipa ''n'' v tip ''p''. Period poluraspada, vedushchij k obrazovaniyu Ga71, dostatochno prodolzhitelen, tak chto podrobnaya ''radioaktivnaya titratsiya'' mozhet soprovozhdat'sya opredeleniem koehffitsienta KHolla i ehlektroprovodnosti. Opyty pokazyvayut takzhe, chto priblizitel'no odin ehlektron na kazhdyj zakhvat nejtrona udalyaetsya defektom reshetki, sozdannym otdachej yadra pri zakhvate ispuskaemykh gamma-luchej. EHti vytesnennye atomy mogut byt' vozvrashcheny obratno na svoe mesto v normal'noj reshetke putem otzhiga pri 450 Degree-Sign C. Byli proizvedeny takzhe nablyudeniya nad dejstviem otdachi v kremnie, prichem bylo ustanovleno, chto na kazhdyj zakhvat ustranyaetsya priblizitel'no 2 nositelya zaryada. Posledstviya ehtikh rezul'tatov, a takzhe rezul'taty v otnoshenii germaniya obsuzhdayutsya v funktsii ot zakhvata spektra gamma-luchej. V sur'myanistom indii zakhvat gamma-luchej iz In{sup 115} nedostatochen dlya togo, chtoby vytesnit' bol'shoe chislo yader, tak chto glavnym vozdejstviem yavlyaetsya obrazovanie Sn{sup 116}, kotoryj stanovitsya donorom pri zamene mesta v reshetke indiya. YAdernaya prisadka predstavlyaetsya perspektivnoj dlya izucheniya mnogochislennykh slozhnykh poluprovodnikov, vvedenie v kotorye primesej khimicheskim sposobom predstavlyaetsya zatrudnitel'nym. (author)

Investigations on Pasteurization of Cold Marinades by {sup 60}Co Gamma Rays; Recherches sur la Pasteurisation a Froid De Marinades par les Rayons Gamma du {sup 60}Co; Issledovaniya pasterizatsii kholodnykh marinadov gamma-luchami; Investigaciones Sobre la Pasteurizacion de Escabeches Frios por Irradiacion Gamma con {sup 60}Co

Energy Technology Data Exchange (ETDEWEB)

Schoenborn, W.; Kinkel, R J.; Hafferl, W. [Battelle Institut e.V., Frankfurt/Main, Federal Republic of Germany (Germany)

1966-11-15

Degree-Sign C los germenes se desarrollan con retraso; mientras que a 22 Degree-Sign C el desarrollo se efectua practicamente sin restricciones, para duplicar la duracion a una temperatura de almacenamiento de 18 Degree-Sign C es necesaria una dosis de 280 krad. Las pruebas organolepticas se basan en analisis de preferencia por aplicacion de la escala hedonistica de nueve puntos y en pruebas de diferenciacion (prueba del triangulo); estas pruebas las realiza un grupo de catadores. A 70 krad el sabor es aun aceptable; a 140 krad hay una neta alteracion del sabor debida a la irradiacion; a 280 krad el sabor es desagradable. Este puede mejorarse bastante por irradiacion a baja temperatura (-30 Degree-Sign C) y adicion de acido ascorbido, sorbitol y condimentos. Prosiguen los experimentos. (author) [Russian] Marinovannoe1 file seledki - jeto rybnyj-produkt, prigotavlivaemyj pod vozdejstviem uksusnoj kisloty i soli i prodavaemyj v rassole, soderzhashhem specii i okolo 3% soli i uksusnoj kisloty (pH 4). Poskol'ku obychnoe dobavlenie predohranjajushhego geksametilentetramina bylo ogranicheno opredelennym periodom vremeni v silu novogo zakona FRG o produktah pitanija, provodilis' issledovanija po pasterizacii s pomoshh'ju ionizirujushhih luchej v kachestve novogo metoda sohranenija bez dobavlenija drugih predohranjajushhih veshhestv. Razlozhenie jetogo pishhevogo produkta vyzyvalos' geterofermentativnymi molochnokislotnymi bakterijami, kotorye dekarboksilirujut aminokisloty, osvobozhdennye iz proteina; razlozhenie bylo rezul'tatom bombardirovki dvuokisi ugleroda. Marinad upakovyvalsja v ploskie banki, soderzhashhie okolo 125 grammov, ipodvergal- sja vozdejstviju gamma-luchej kobal'ta-60 iz nashego podvodnogo istochnika pri ohlazhdenii. Obluchenie uvelichilo sroki hranenija marinada v konservnyh bankah. Period do bombardirovki pri 15 Degree-Sign S v sluchae obluchenija 155 kradami byl v tri raza bol'she chem obychno. Kriticheskoe chislo v 1 mln. mikrobov na millilitr pri 15