Energy Technology Data Exchange (ETDEWEB)
Sproull, R L; Slack, G A; Moss, M; Pohl, R O; Krumhansl, J A [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY (United States)
1962-01-15
indicadores anadidos. La segunda aplicacion consiste en introducir en los haluros alcalinos pequenas cantidades de iones-impureza a fin de poder estudiar la dispersion de fonones causada por dichas impurezas, o por los huecos que crean en la red cristalina; los autores efectuan las mediciones correspondientes a temperaturas muy bajas, ya que en tales condiciones las imperfecciones de la red imponen limitaciones al libre recorrido medio de los fonones. En estos trabajos han empleado generalmente el radioisotopo {sup 45}Ca. Los autores pasan revista a los resultados de su labor, citan algunas aplicaciones actuales de los radioisotopos en este campo y formulan observaciones sobre sus posibles aplicaciones en lo futuro. (author) [Russian] Radioizotopy byli ispol'zovany v dvukh vazhnykh napravleniyakh dlya izucheniya defektov v shchelochnykh galoidnykh kristallakh. Zonal'noe rafinirovanie soedinenij proveryalos' izotopnymi indikatorami, a koehffitsienty izolyatsii opredelyalis' iz poluchennykh dannykh. Drugoe primenenie zaklyuchalos' v vvedenii nebol'shikh kontsentratsij primesej ionov v shchelochnye galoidy s tem, chtoby izuchit' rasseyanie fononov takimi defektami ili vakansiyami, imi vyzyvaemymi; ehti izmereniya proizvodyatsya pri ochen' nizkikh temperaturakh, pri kotorykh srednyaya velichina svobodnogo probega fonona ogranichivaetsya defektami reshetki. Radioizotopom, poluchivshim naibolee shirokoe primenenie, yavlyaetsya kal'tsij-45. (author)
Energy Technology Data Exchange (ETDEWEB)
Gorban' , I S; Gumenyuk, A F; Omel' yanenko, V A [Kievskij Gosudarstvennyj Univ., Kiev (Ukrainian SSR)
1989-11-01
Thermoluminescence (TL) of initial and thermally treated purposely undoped crystals of barium niobate - sodium has been studied within 85-400 K. The TL intensity is found to depend on the temperature to which the sample has been heated. A conclusion is drawn that nonstationarity of the TL properties is due to slowly occuring processes of compensation of pyrocharge, which depend on the temperatural prehistory of the sample. A mechanism of the traps transformation in a strong pyrofield of high-impedance crystals is discussed.
Energy Technology Data Exchange (ETDEWEB)
Radchenko, I R; Filimonova, L A [Moskovskij Inzhenerno-Fizicheskij Inst., Moscow (Russian Federation)
1993-06-01
The patterns of polarized beam interference (conoscopic patterns) enable assessment of orientation and parameters of crystal's optical indicatrix. The presented conoscopic patterns of gadolinium molybdate crystal in the vicinity to plane and wedge-live domain walls differ from conoscopic patterns of the crystals far away from these walls which allows to spear about changes occurring in the crystal in the vicinity to domain walls.
Energy Technology Data Exchange (ETDEWEB)
Vakhidov, Sh A; Nuritdinov, I; Musaeva, M A [Inst. Yadernoj Fizili AN Uzbekistana, Tashkent (Uzbekistan)
1999-08-01
The photoluminescence characteristics of the proper radiation color centers of the MgF{sub 2} crystals are studied. The samples were irradiated by the {sup 60}Co source {gamma}-rays up to the dose 10{sup 7}Gy. The bands with the maxima in the area of 420, 460, 550 and 620 nm were identified, which are excited correspondingly in the bands with the maxima of 370, 320, 410 and 480 nm.
Energy Technology Data Exchange (ETDEWEB)
Khushvakov, O B
1992-01-01
Radiation defects production processes in pure and doped quartz crystals with various structure defectness, caused by preliminary irradiation with neutrons, protons, deuterons and {alpha}-particles, during various electron excitation densities were investigated. The distribution of colour centres along the thickness of irradiated quartz crystals was measured. It was supposed that colour centres are produced on account of inelastic energy losses as the result of collective decay of two or more interacting excitons. It was shown that in quartz crystals under the actions of protons with overthreshold energy 18 MeV and electrons with subthreshold energy 100 keV the same structure defects are formed. It was established that radiation defect production process has two stages. The first stage reveals radiation defects produced by preliminary irradiation. The second one reveals additional intrinsic defects formed under the action of gamma-rays and electrons. The probability dependence of defect production on neutron fluence and masses of incident particles was studied. It was supposed that the creation of additional defects in preliminary irradiated crystals is due to non-radiative decay of electron excitations near radiation-induced defects. It was shown that increase of impurity concentration leads to rate growth of accumulation of radiation induced defects. (A.A.D.) 15 refs. 4 figs.
Energy Technology Data Exchange (ETDEWEB)
Popov, A I [AN Latvijskoj SSR, Riga (USSR). Inst. Fiziki
1990-01-01
Thermal stability of the radiation defects produced in KBr-In by optical creation of the electronic excitation (optical creation of the excitons or optical ionization of In{sup +}-ions under C-band illumination) is investigated by the method of thermostimulated luminescence (TSL). A method of detection of prehistory defects, when the optical ionization of In{sup +}-ions and TSL are performed, is proposed. Quadratic dependence of V{sub 2}-center creation upon dose is shown. This dependence confirms assocative mechanism of the creation of V{sub 2}-centers from two interstitial centers.
Energy Technology Data Exchange (ETDEWEB)
De Vries, L J; Udo, F [Instituut voor Kernphysisch Onderzoek, Amsterdam (Netherlands)
1962-04-15
Presented is a proton-electron discrimination circuit, based on the pulse-form differences between proton and electron-induced scintillation light pulses in stilbene. The circuit is stable and resolves proton from electron pulses down to a proton energy of 300 keV. The discrimination circuit, which contains only linear elements, is sensitive to pile-up-induced errors for only 0.1 {mu}s after the arrival of a pulse. The described circuit has now been used in a 1-30 MeV neutron spectrometer based on proton-recoil between two silbene crystals. A resolution of 10% at 14 MeV neutron energy was obtained with a detection efficiency of 1.3 x 10{sup -4}. A neutron monitor, also based on linear pulse-form discrimination, could be used to measure a neutron dose of 10% of the maximum permissible dose in the presence of a gamma flux of 4 times the maximum permissible dose. (author) [French] Le memoire decrit un circuit de discrimination proton/electron dont le principe repose sur les differences de forme entre les impulsions lumineuses dans du stilbene, produites par des protons, d'une part, et des electrons, d'autre part. Le circuit est stable et permet de separer les impulsions protoniques des impulsions electroniques, a partir d'une energie protonique de 300 keV. Ce circuit, qui ne contient que des elements lineaires, n'est sujet a des erreurs dues a l'accumulation que pendant 0,1 {mu}s apres l'arrivee de l'impulsion. Il a ete utilise dans un spectrometre neutronique de 1-30 MeV, fonde sur le recul des protons entre deux cristaux de stilbene. On a obtenu une resolution de 10% pour une energie neutronique de 14 MeV, avec une efficacite de detection de 1,3x10{sup -4}. Un detecteur de neutrons procedant egalement par discrimination d'apres la forme des impulsions, pourrait servir a mesurer une dose de neutrons representant 10% de la dose maximum admissible, en presence d'un flux gamma correspondant a une dose quatre fois superieure a la dose maximum admissible. (author) [Spanish] Los autores presentan un circuito de discriminacion proton-electron basado en las diferencias de forma entre los impulsos de centelleo luminosos producidos por los protones y por los electrones, respectivamente, en los cristales de estilbeno. El circuito es estable y es capaz de distinguir los impulsos de protones de los electrones hasta con energias de protones de solamente 300 keV. El circuito discriminador, compuesto unicamente de elementos lineales, es sensible a errores inducidos por apilonamiento durante 0,1 {mu}s solamente, a partir de la llegada de un impulso. El circuito descrito se aplico en un espectrometro para neutrones de 1 a 30 MeV, basado en el retroceso de protones entre dos cristales de estilbeno. Se alcanzo un poder de resolucion de 10 por ciento, para una energia neutronica de 14 MeV, con un rendimiento de deteccion de 1,3 {center_dot} 10{sup -4}. Se podria usar un monitor neutronico basado tambien en un sistema de discriminacion lineal de la forma de los impulsos para medir una dosis neutronica igual al 10% de la dosis maxima admisible, en presencia de un flujo {gamma} cuatro veces mayor que la dosis maxima admisible. (author) [Russian] Opisyvaetsya kontur diskriminatsii protonov-ehlektronov, osnovannyj na raznitse formy stsintillyatsionnykh svetovykh impul'sov, navedennykh v stil'bene sootvetstvenno protonami i ehlektronami. EHtot kontur ustojchiv i otlichaet impul'sy protonov ot impul'sov ehlektronov dazhe pri padenii ehnergii protonov do 300 kehv. Diskriminiruyushchij kontur, sostoyashchij isklyuchitel'no iz linejnykh ehlementov, chuvstvitelen k obrazuyushchimsya iz-za nakopleniya oshibkam tol'ko v techenie 0,1 mikro-sekundy posle postupleniya impul'sa. Opisyvaemyj kontur byl ispol'zovan v spektrometre dlya nejtronov s ehnergiyami 1-30 mehv, osnovannom na otdache protonov mezhdu dvumya kristallami stil'bena. Pri ehnergii nejtronov v 14 mehv bylo polucheno ikh razreshenie s tochnost'yu do 10%, pri ehffektivnosti detektirovaniya v 1,3 x 10{sup -4}. Dlya izmereniya dozy nejtronov, ne prevyshayushchej 10% maksimal'noj dopustimoj dozy i pri nalichii potoka gamma-luchej, prevyshayushchego v 4 raza maksimal'nuyu d o p u s t i m uyu dozu, byl ispol'zovan kontrol'no-izmeritel'nyj dozimetricheskij schetchik, takzhe osnovannyj na linejnoj diskriminatsii formy impul'sov. (author)
Energy Technology Data Exchange (ETDEWEB)
Lambe, J [Physics Department, Ford Motor Company, Scientific Laboratory, Dearborn, MI (United States)
1962-01-15
moleculaire solide. Les experiences effectuees montrent que l'emploi de ce procede est tout a fait possible et devrait convenir plus particulierement a la production de radicaux libres dans les matieres organiques dont la radioresistance est assez forte. (author) [Spanish] El estudio de los defectos que aparecen en los cristales casi perfectos constituye uno de los capitulos mas interesantes de la fisica del estado solido. Por lo tanto, la creacion controlada de los defectos deseados representa un aspecto primordial de esos estudios. Dos de los metodos que mas se emplean para introducir defectos de esta clase consisten en agregar deliberadamente impurezas quimicas y en radioinducir danos. El autor ha estudiado la posililidad de valerse de la desintegracion radiactiva para crear defectos en los solidos, La tecnica se basa simplemente en obtener un material lo mas perfecto posible, pero en el que algunos de los atomos del cristal consistan en isotopos radiactivos del mismo elemento. Al desintegrarse estos atomos, el elemento descendiente origina un defecto. A fin de comprobar la posibilidad de aplicar esta tecnica, el autor preparo atomos de tritio incorporados en cristales de tritio molecular solido. Los experimentos indican que el metodo es viable, y que deberia poder aplicarse ante todo a la separacion de aquellos radicales libres contenidos en sustancias organicas que sean bastante resistentes a los danos ocasionados por las radiaciones. (author) [Russian] Odnoj iz naibolee interesnykh oblastej fiziki tverdogo sostoyaniya yavlyaetsya izuchenie defektov v pochti sovershennykh kristallakh. Takim obrazom, umyshlennoe obrazovanie takikh defektov yavlyaetsya vazhnym aspektom ehtikh issledovanij. Dlya proizvodstva takikh defektov byli shiroko rasprostraneny metody khimicheskikh dobavlenij i povrezhdeniya radiatsiej. V nastoyashchem trude rassmatrivayutsya nekotorye vozmozhnosti ispol'zovaniya radioaktivnogo raspada dlya obrazovaniya defektov v tverdykh telakh. Metod ehtot
Energy Technology Data Exchange (ETDEWEB)
Schmidt, G. B. [Institut fuer Kernchemie der Universitaet Koeln, Cologne, Federal Republic of Germany (Germany)
1965-10-15
The kinetics of isotopic exchange reactions give information about the lability of complexes in solution and about the mechanisms of substitution. The exchange of {sup 82}Br-labelled [Rh(NH{sub 3}){sub 5}Br]{sup 2+} and [Ii(NH{sub 3}){sub 5}Br]{sup 2+} complexes with Br{sup -} ions, of trans-[Rh(en){sub 2}Cl{sub 2}]{sup +} and trans- [Co(en){sub 2} Cl{sub 2}]{sup +}]+ with Cl{sup -} ions, of trans- [Co(en){sub 2}Br{sub 2}]{sup +} with Br{sup -} and of [OSCl{sub 6}]{sup 2-} and [OsI{sub 6}]{sup 2-} with Cl{sup -} and I{sup -} ions, respectively, was investigated in acid solutions. The iridium pentamminebromo complex exchanges about 60 times slower than the corresponding rhodium pentamminebromo complex. The rate constant for the Rh- complex was found to be k = (1.03 {+-} 0,02) x 10{sup -2} min{sup -1} at 100 Degree-Sign C, for the Ir-complex k{sub 100 Degree-Sign C} = 1.7 x 10{sup -4} min{sup -1}. For both complexes the exchange rate R is first-order in the complex concentration; in acid solution R is nearly independent of the bromide and hydrogen concentration as well as of the ionic strength. This indicates that the exchange takes place by a dissociation mechanism. Activation energies of 24 and 23 kcal/ mole forthe Rh- and Ir-complex, respectively, were calculated. Rate constants of the {sup 36}Cl isotopic exchange between 60 and 100 Degree-Sign C were measured for the trans- [Rh(en){sub 2} Cl{sub 2}]{sup +} complex and an Arrhenius activation energy of 25 kcal/mole was determined. Here again the increase of the rate R is of first order in the complex concentration; but it is only slightly dependent on the hydrogen and chloride concentration. The exchange seems to occur by aquation. In methanolic HCl solution the exchange rate of this complex is immeasurably slow at 60 Degree-Sign C. The halide exchanges of trans-[Co(en){sub 2} Cl{sub 2}]{sup +} and trans [Co(en){sub 2} Br{sub 2}]{sup +} were measured in methanolic solutions between 30 and 60 Degree-Sign C. Further , the halide exchange of [OsCl{sub 6}]{sup 2-} and [Osl6]{sup 2-} was investigated in hydrochloric acid and hydroiodic acid, respectively, in methanolic acid and in ethanolic acid solution. The rates measured are compared with earlier results of the isotopic exchange of the corresponding hexabromo complex. Beside these investigations of the dissolved complexes, displacement reactions of labelled cis- and trans-[Co(en){sub 2}Cl*{sub 2}] Cl and trans- [Rh(en){sub 2}Cl*{sub 2}] Cl in the lattice were studied. The half-time of the exchange for both solid isomeric Co complexes is about 4 h at 150 Degree-Sign C. For the Rh complex a half-time of about 26 h was found at 225 Degree-Sign C. Activation energies of 30-35 kcal/mole were calculated. X-ray irradiation leads to an exchange increasing with the dose. In addition, the thermal exchange of irradiated crystals is accelerated. In contrast to the ethylenediamine complexes, the solid Rh and Ir pentamminebromo bromides or chlorides exchange only very slowly by raising the temperature even to 210 Degree-Sign C. But in these solid complexes ''activated'' exchange reactions take place if the complex receives excitation energy from a nuclear process such as the {sup 80m}Br -> {sup 80}Br isomeric transition. This phenomenon was investigated in some detail. (author) [French] La cinetique des echanges isotopiques donne des renseignements sur la labilite des complexes en solution et sur les mecanismes de substitution. L'echange des complexes [Rh(NH{sub 3}){sub 5}Br]{sup 2+} et [Ir(NH{sub 3}){sub 5}Br]{sup 2+}]{sup 2+} marques au {sup 82}Br avec des ions Br{sup -}, de trans- [Rh(en){sub 2}Cl{sub 2}]+ et de trans- [Co(en){sub 2}Cl{sub 2}]+ avec des ions Cl{sup -}, de trans- [Co(en){sub 2}Br{sub 2}]{sup +} avec des ions Br{sup -} et de [OsCl{sub 6}]{sup 2-} et [Osl{sub 6}]{sup 2-} avec des ions Cl{sup -} et I{sup -} respectivement a ete etudie en solution acide. Pour le complexe de pentamminebromo-iridium, l'echange est environ 60 fois plus lent que pour le complexe correspondant de pentamminebromo-rhodium. Les constantes de vitesse pour le complexe au rhodium sont k{sub 100 Degree-Sign C} = (1,03 {+-} 0,02). 10-2 min-1 et pour le complexe a l'iridium k{sub 100 Degree-Sign C} = 1.7 * 10{sup -4} jnm{sup -1}. Pour les deux complexes la vitesse d'echange R est du premier ordre en concentration du complexe; en solution acide, R est presque independante de la concentration en bromure et en hydrogene ainsi que de la force ionique, ce qui montre que l'echange se produit par un mecanisme dissociatif. En calculant les energies d'activation pour le complexe au rhodium et pour le complexe a l'iridium, l'auteur a trouve des valeurs de 24 et de 23 kcal/ mole respectivement. Les constantes de vitesse de rechange isotopique de {sup 36}Cl entre 60 et 100 Degree-Sign C ont ete mesurees pour le complexe trans-[Rh(en){sub 2}Cl{sub 2}]{sup +} et on a determine une energie d'activation d'Arrhenius de 25 kcal/mole. La aussi, l'augmentation de la vitesse R est du premier ordre en concentration du complexe; mais il ne depend que faiblement de la concentration en hydrogene et en chlorure. Il semble que rechange se produise par <
Energy Technology Data Exchange (ETDEWEB)
Jones, L W; Perl, M L [Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI (United States); Lawrence Radiation Laboratory, University of California, Berkeley, CA (United States)
1962-04-15
los protones de retroceso procedentes de la dispersion inelastica de piones (produccion de piones aislados) en tres cantidades de movimiento correspondientes a piones incidentes. En este caso se registraron tambien varios millares de sucesos. El alcance y el angulo del proton de retroceso determinaron exclusivamente la transferencia de cantidad de movimiento y la energia del centro de masa del sistema di-pion, que fueron los parametros cinematicos de interes en este problema. En estos experimentos se logro un disparo despues de cada suceso y un tiempo de resolucion de 5 {mu}s, desbloqueando el segundo tubo de imagenes al recibir una senal del circuito electronico del contador de centelleo. Los autores estudian la preparacion y la ejecucion con exito de estos experimentos, sobre todo las caracteristicas mas interesantes de los tubos de imagenes de los contadores de centelleo y de los sistemas electronicos. Se ha adquirido tambien experiencia en el analisis de fotografias de trazas, en particular respecto de la precision alcanzable y la exactitud de los datos fisicos obtenidos. Por ultimo examinan la evolucion futura de las camaras luminiscentes, en especial de los tubos intensificadores de imagenes y los centelleadores en desarrollo actualmente. Tambien analizan el papel que la camara luminiscente podra desempenar en los futuros experimentos con particulas de elevada energia, en comparacion con las camaras de chispa y otros detectores. (author) [Russian] Vpervye v ehksperimentakh v oblasti fiziki chastits vysokikh ehnergij byla ispol'zovana lyuminestsentnaya kamera. Na bevatrone radiatsionnoj laboratorii im. Lourensa s pomoshch'yu kaskadnoj sistemy trekh usilitelej yarkosti izobrazheniya byli sfotografirovany sledy chastits v aktivirovannykh jodisto-natrievykh kristallakh. Pri odnom ehksperimente uprugoe rasseyanie pi-mezonov na protonakh izuchalos' s pomoshch'yu dvukh blokov stsintillyatorov, kazhdyj iz kotorykh imel dlinu 20 sm, prichem odin ispol'zovalsya dlya