Search results for "nuclear fusion"
showing 10 items of 437 documents
Level lifetimes in neutron-rich Ru isotopes
1995
The neutron-rich Ru isotopes are situated between the strongly deformed Sr-Zr region with axial deformation of f l _ 0.40 [1] and the spherical Cd-Sn region. Evidence for triaxiality of even-even Ru isotopes has been presented in [2-5], and lifetimes of some of their 2 + states have been measured in fission studies [6-9]. It seems, however, that in these experiments the nearly identical energies of the 2 + ---* 0 + transitions in l~ and 11~ could not be separated. Therefore, high-resolution measurements are required in order to perceive the evolution of deformation with increasing neutron number. So far only few measurements by the delayed-coincidence method [10] have been performed on chem…
Determination of the partial electron capture- and spontaneous-fission half-lives of254No
1988
The isotope254No was produced in the fusion reaction48Ca +208Pb. Using the velocity filter SHIP and radiochemical techniques it was found that the nuclide254No with a half-life of 55 s decays byα, EC, and spontaneous-fission. Deduced partial half-lives are (61±2) s forα-decay, (550−160+370) s for EC and [2.2−1.0+2.0]×104 s for spontaneous fission.
Competition between binary reactions and fusion in heavy-ion collisions at the Coulomb barrier
1992
Mass and charge distributions for binary reaction channels have been measured for the reactions86Kr with76Ge,104Ru and130Te at the Coulomb barrier using chemical separations andγ-ray spectroscopy. These systems span the region where dynamical hindrance to complete fusion sets in. The binary reactions can be subdivided into two components associated withi) reflection from the outer potential barrier (quasielastic), andii) reseparation after passing the barrier (complex reactions). The sum of complex-reaction channels and evaporation residues from complete fusion can be reproduced by a barrier passing calculation. The fraction of the barrier passing flux leading to reseparation increases from…
Alpha decay of the new isotopes207, 208Ac
1994
Two new neutron-deficient isotopes207,208Ac have been produced in fusion reactions with 5.2–5.6 MeV/nucleon40Ar ions on175Lu and identified on the basis of genetic correlations. The fusion evaporation products were separated on-line using a gas-filled magnetic recoil separator. The alpha energy and half-life of208Ac were determined to be (7572±15) keV and (95 −16 +24 ) ms, respectively. A new alpha line with a half-life of (25 −5 +9 ) ms and an energy of (7758±20) keV is assigned to the decay of an isomeric state in208Ac. Another new activity with a half-life of (22 −9 +40 ) ms and an alpha energy of (7712±25) keV is assigned to207Ac.
Reaction Dynamics at the Barrier for Heavy Compound
2004
To investigate basic properties of the fusion reaction dynamics for heavy compound systems the partial wave distribution σ l extracted from measured γ multiplicities can be employed as an alternative to the classically used fusion/fission excitation functions. A variety of reactions leading to compound nuclei (CN) in the Pb region can be used to investigate features like the fusion-fission competition, the role of deformation in the fusion of heavy systems and a possible effect of the Z=82 shell on the enhancement of evaporation residue (ER) production. The measured spin distribution (SD) can provide information on the single partial wave cross sections which is hidden in the integral fusio…
Spin distributions at the Coulomb barrier in the $^{58}$Ni+$^{60}$Ni fusion reaction from gamma-ray multiplicity measurements
2002
Abstract Heavy-ion fusion barrier distributions are now routinely obtained directly from experimental data. Measurements of the total γ-ray multiplicity for the fusion channels of the 58 Ni + 60 Ni system, which has striking yet well understood barrier structures, confirm the theoretical predictions that very high spins can be populated at energies close to (and even below) the nominal Coulomb barrier. The mapping from multiplicities to spin populations shows that structures in the barrier distribution are still evident in the γ-ray results.
Evidence for three microscopically different kinds ofE1 transition in lead-region nuclei
1988
A survey of electric dipole transition rates, or B(E1) values, is done for lead-region nuclei with 82≦Z≦90 and 112≦N≦134. It is found that the major part of the E1 transitions are hindered by a factor of about 106–107 and these transitions are interpreted to proceed via admixtures of the collective 1− state. A second group, which is generally 10–100 times less hindered and is involving the πi13/2 orbital in the initial states, is suggested to proceed via the allowed πi11/2→πh9/2 admixtures in the wave functions. These two groups are compared to a third newly established category, the α-cluster or IBAp-boson mode, of the so-called vibron model.
Rotational bands in99Sr
1984
The β-decay of 59 ms99Rb has been studied at OSTIS. As is confirmed by RPA calculations with Nilsson model wave functions, the lowest energy levels in99Sr are consistent with rotational bands built on the [411 3/2], [413 5/2] and [422 3/2] Nilsson neutron configurations at 0, 423 and 1071 keV, respectively. All three bands have similar values of the inertial parameter ħ2/2θ indicating a nearly rigid rotor.
Level structure of120Sn from the decay of120In and120Sb isomers
1971
Gamma rays in the decay of the 3.2 s (1+) and 44 s (4, 5+)120In isomers and the 15.9 min (1+) and 5.8 d (8−)120Sb isomers have been investigated using Ge(Li) spectrometers and prompt and delayed Ge(Li)-NaI(Tl) coincidence techniques. The constructed level scheme of120Sn contains 18 levels at the following energies (keV): 0 (0+), 1171.6 (2+), 1875.6 (0+), 2096.9 (1, 2, 3), 2160.7 (0+), 2195.0 (4+), 2284.8 (5−), 2355.6 (2+), 2421.2 (1, 2, 3), 2466.3 (4+), 2482.1 (7−), 2643.5 (4+), 3058.6 (4+), 3179.7 (4+), 3349.9 (3, 4+), 3440 (3, 4+), 3447.6 (5, 6+) and 3777 (4+). The levels are compared with the levels obtained from recent charged-particle reaction studies and the structure of120Sn is brief…
Aufbau eines automatisch arbeitenden ??2-Spektrometers und Untersuchung des Konversionslinienspektrums von In114m und ThB mit Folgeprodukten
1963
An automatically operatedπ√2 spectrometer is described. The regulated current supply is transistorized. With this spectrometer the electron spectra of In114m and of ThB with daughter products have been investigated. TheK/L ratio of the 191 keV isomeric transition in In114m was found to be 1·25±0·03, in excellent agreement with the theoretical value ofSliv andBand. In the electron spectrum of ThB and daughter products 46 lines were found betweenBϱ=1750Г cm andBϱ=10000Г cm. Some of them are new. Most important is a new weak line atBϱ=7030Г cm which fixes a new level atE=1·807 MeV in ThC′ (Po212). Simultaneously the earlier reported discrepancy between electron andγ-ray intensities for 1·8 MeV…