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

Kaskadni gamma raspadi složene jezgre 177Lu i njene posebnosti

From the mass of γ-γ coincidences registered by a pair of Ge-detectors after thermal neutron capture in 176Lu, the intensity distributions of the two-step cascades proceeding between the compound state and eight low-lying ( 122 ≤ Eex ≤ 637 keV) levels of 177Lu were obtained. The analysis of the intensity distribution of all the cascades resolved experimentally and of the total distribution, including unresolved cascades, showed that the correct description of the cascade γ-decay process for the odd-even deformed nucleus should account for the strong influence of vibrational-type excitations below 3 MeV and an abrupt transition from vibrational to quasiparticle excitations above this energy.Na osnovi velikog broja γ-γ sudesa od uhvata termičkih neutrona u 176Lu, zabilježenih pomocu dva Ge-detektora, izvedene su raspodjele intenziteta kaskada parova fotona od prijelaza sa stanja složene jezgre preko međustanja na osam niskih ( 122 ≤ Eex ≤ 637 keV) stanja 177Lu. Analiza svih raspodjela intenziteta prijelaza koji su bili razlučeni i ukupne raspodjele, uključivši i nerazlučene kaskade, pokazuje da opis kaskadnih γ-raspada ove deformirane neparno-parne jezgre mora uzeti u obzir snažan utjecaj vibracijskih uzbuđenih stanja za stanja ispod 3 MeV, te nagao prijelaz od vibracijskih ka kvazičestičnim stanjima iznad te energije

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

Glavne posebnosti kaskadnog raspada složene jezgre 176lu

The two-step γ-cascades, following thermal neutron capture in 175Lu and terminating at 14 low-lying (Eex < 600 keV) levels or level doublets of the 176Lu nucleus, have been studied using the sum-coincidence technique using two Ge-detectors. The parameter majority of these cascades was unambiguously placed in the decay scheme. The regularity in the energies of the most intense cascades has been revealed. The results are compared with previous data for a group of deformed and spherical nuclei and with predictions of different models.Primjenom sudesno-zbrojne metode, uz upotrebu dvaju Ge-detektora, proučavale su se dvostupne γ-kaskade nastale uhvatom termičkih neutrona u 175Lu koje završavaju na 14 niskoležećih (Euzb < 600 keV) stanja ili dubleta jezgre 176Lu. Odredili su se parametri 350 najintenzivnijih kaskada. Veći njihov dio složen je u shemu raspada. Utvrdila se je pravilnost energija najintenzivnijih kaskada. Ishodi se uspoređuju s ranijim podacima za grupu sferičnih i izobličenih jezgri i s predviđanjima drugih modela

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