Determination of particulate sizes in ceramic powders by electron microscopy

Ceramic powders of small particulate size can be characterized by electron microscopy. The usual methods of powder preparation were tested and compared. The data are analyzed in two ways

Physical properties of interplanetary grains

Morphological analyses of micrometeorite craters found on lunar rocks and laboratory simulation experiments are used to formulate a meteoritic interplanetary dust particle for optical scattering calculations that is roughly spherical and has a density of 2g cm/3. The model particle has chondritic elemental abundances and also contains a high content of finely dispersed carbon

Dvojne kaskade nakon uhvata termičkih neutrona u 27Al

Cascades of two successive γ-transitions following thermal neutron capture in 27Al have been studied. From γ − γ coincidences accumulated in the experiment, 13 intensity distributions of two-step cascades terminating at low-lying levels of 28Al have been determined. From these spectra, the energies of γ-transitions and intensities of 249 cascades populating 123 intermediate levels were derived. Energy dependence of intensity summed over the 0.5 MeV energy intervals for the cascades to two lower levels has also been determined.Proučavali smo kaskade dvaju uzastopnih γ-prijelaza koji slijede uhvat termičkih neutrona u 27Al. Na osnovi u mjerenju sakupljenih γ − γ sudesa, odredili smo 13 raspodjela intenziteta dvojnih kaskada koje završavaju na niskim stanjima 28Al. Iz tih smo spektara izveli energije γ-prijelaza i intenzitete 249 kaskada koje prolaze preko 123 međustanja. Odredili smo također energijsku ovisnost intenziteta zbrojenih preko intervala širine 0.5 MeV za kaskade prema dvama nižim stanjima

Dvojne kaskade nakon uhvata termičkih neutrona u 27Al

Cascades of two successive γ-transitions following thermal neutron capture in 27Al have been studied. From γ − γ coincidences accumulated in the experiment, 13 intensity distributions of two-step cascades terminating at low-lying levels of 28Al have been determined. From these spectra, the energies of γ-transitions and intensities of 249 cascades populating 123 intermediate levels were derived. Energy dependence of intensity summed over the 0.5 MeV energy intervals for the cascades to two lower levels has also been determined.Proučavali smo kaskade dvaju uzastopnih γ-prijelaza koji slijede uhvat termičkih neutrona u 27Al. Na osnovi u mjerenju sakupljenih γ − γ sudesa, odredili smo 13 raspodjela intenziteta dvojnih kaskada koje završavaju na niskim stanjima 28Al. Iz tih smo spektara izveli energije γ-prijelaza i intenzitete 249 kaskada koje prolaze preko 123 međustanja. Odredili smo također energijsku ovisnost intenziteta zbrojenih preko intervala širine 0.5 MeV za kaskade prema dvama nižim stanjima

Jake dvojne kaskade i shema γ-raspada složene jezge 118Sn

Transition energies and intensities of 453 two-step cascades following thermal neutron capture in 117Sn have been measured. The data allowed us to considerably extend previous decay scheme of the 118Sn nucleus and to achieve more precise results. Autocorrelation analysis of the excitation spectrum of intermediate levels of the most intense cascades allowed us to determine most probable period of their regularity. Besides, analysis showed the impossibility to reproduce quantitatively the total cascade intensities taking into account only excitations of the fermion type. The results lead to the conclusion that the excitations of vibrational type considerably influence the cascade g-decay process in 118Sn almost up to the neutron separation energy Sn.Mjerili smo energije i intenzitete 453 dvojne kaskada koje slijede uhvat termalnih neutrona u 117Sn. Podaci su omogućili određivanje znatno proširenje ranije sheme raspada jezgri 118Sn i točnije rezultate. Analiza autokorelacije uzbudnog spektra međustanja najjačih kaskada omogućila je određivanje vjerojatne periodičnosti. Pokazuje se da nije moguće kvantitativno objasniti ukupne jakosti kaskada ako se uzmu u obzir samo fermionske uzbude. Zaključuje se da vibracijske uzbude znatno utječu na γ-raspade u 118Sn sve do energije odvajanja neutrona Sn

Kaskadni γ-raspad složene jezgre 193Os i neki izgledi dinamike promjena nuklearnih osobina ispod Bn

Two-step cascades from the 192Os(nth, γ)193Os reaction were studied in a γ − γ coincidence measurement with two HPGe detectors. The decay scheme of 193Os was established up to the excitation energy of about 3 MeV. The excitation spectrum of intermediate levels of most intense cascades was found to be practically harmonic.Mjerili smo γ−γ kaskade u reakciji 192Os(nth, γ)193Os sudesnom metodom s dvama Ge detektorima. Utvrdili smo shemu raspada 193Os do uzbudne energije ∼ 3 MeV. Našli smo da je spektar viših međustanja najintenzivnijih kaskada gotovo harmoničan

Dvofotonske kaskade u γ raspadu složene jezgre 187w

Two-step cascades from the 186W(n,2γ) 187W reaction have been studied in the γ−γ coincidence experiment carried out in Reˇz. Their total intensity is evaluated with ˇ respect to the final level of cascades at ≈ 1.9 MeV. The processes of the cascade γ-decay of this nucleus, like of all nuclei previously studied in analogous experiments, can not be described without taking into account the influence of nuclear structure at energies lower than at least a half of the neutron-binding energy. The decay scheme of 187W, including 386 cascades, is determined up to the excitation energy ∼ 3 MeV. It contains data about 196 excited levels of this nucleus with the most probable spins 1/2 and 3/2. As in the earlier studied nuclei, the population of the intermediate levels by the most intense cascades may indicate a harmonic character of the states involved.Proučavamo dvofotonske kaskade iz reakcije 186W(n,2γ) 187W mjerenjem γ−γ koincidencija izvedenih u Režu. Odredili smo njihove ukupne intenzitete u odnosu na konačno stanje dosegnuto kaskadom u području energije ≈ 1.9 MeV. Procesi kaskadnih raspada u ovoj jezgri, kao i u sličnim ranijim mjerenjima, ne mogu se opisati ako se ne uzme u obzir nuklearna struktura na energijama nižim od barem polovice energije vezanja neutrona. Odredili smo shemu raspada 187W, uključivši 386 kaskada do energije uzbude ∼ 3 MeV. Shema sadrži 196 viših stanja te jezgre, a najvjerojatniji spinovi tih stanja su 1/2 i 3/2. Kao i u ranijim proučavanjima, popunjavanje međustanja najintenzivnijim kaskadama možda ukazuje na njihova harmonijska svojstva

Dvojne kaskade u raspadu složene jezgre 185w

Two-step cascades from the 184W(nth, γ)185W reaction were studied in a γ − γ coincidence measurement. The total intensity of cascades terminating at levels with the energy ≤ 2.2 MeV was estimated for the first time. The decay scheme of 185W including 781 cascades was established up to the excitation energy \u27 3.3 MeV. As in the nuclei studied earlier, the excitation spectrum of intermediate levels of the most intense cascades was found to be harmonic.Istraživali smo dvojne kaskade u reakciji 184W(nth, γ)185W sudesnim mjerenjem γ − γ. To su prva mjerenja ukupnih intenziteta kaskada koje završavaju na energiji uzbude ≤ 2.2 MeV. Utvrdili smo shemu raspada 185W sa 781 kaskada s enegijom uzbude oko 3.3 MeV. Kao i u ranijim istraživanjima, nalazimo da je spektar uzbude međustanja za najintenzivnije kaskade harmoničan