Search results for "fission"
showing 10 items of 421 documents
Accurate Fission Data for Nuclear Safety
2013
The Accurate fission data for nuclear safety (AlFONS) project aims at high precision measurements of fission yields, using the renewed IGISOL mass separator facility in combination with a new high current light ion cyclotron at the University of Jyvaskyla. The 30 MeV proton beam will be used to create fast and thermal neutron spectra for the study of neutron induced fission yields. Thanks to a series of mass separating elements, culminating with the JYFLTRAP Penning trap, it is possible to achieve a mass resolving power in the order of a few hundred thousands. In this paper we present the experimental setup and the design of a neutron converter target for IGISOL. The goal is to have a flexi…
Spontaneous fission lifetimes from the minimization of self-consistent collective action
2013
The spontaneous fission lifetime of 264Fm has been studied within nuclear density functional theory by minimizing the collective action integral for fission in a two-dimensional quadrupole collective space representing elongation and triaxiality. The collective potential and inertia tensor are obtained self-consistently using the Skyrme energy density functional and density-dependent pairing interaction. The resulting spontaneous fission lifetimes are compared with the static result obtained with the minimum-energy pathway. We show that fission pathways strongly depend on assumptions underlying collective inertia. With the non-perturbative mass parameters, the dynamic fission pathway become…
(e,e′f)-Coincidence Experiments on Uranium Isotopes
1986
(e,e′f)-coincidence experiments represent the most powerful tool to investigate the decay properties of giant multipole resonances, especially of the isoscalar giant quadrupole resonance (GQR), in heavy nuclei. Besides the advantages of the inelastic electron scattering, the coincidence between the fission fragments and the scattered electron causes a complete suppression of the huge radiation tail. The study of the fission decay of giant resonances in heavy nuclei provides interesting information about the coupling of the collective phenomena of fission and giant resonances. In particular the fission decay of the GQR has been subject of controversial experimental studies, using hadrons [1]…
Pre- and post-scission neutron emission in the reaction180Hf(40Ar, fission) atE lab=216 MeV
1996
Neutron and fission fragment spectra following the180Hf(40Ar,f) reaction atE lab=216MeV were measured. The following neutron total, pre- and post-scission multiplicities were extracted:M tot =7.2±1.3,M pre =2.7±0.9,M post =4.5±0.9. The average temperature parameters of the neutron spectra areT pre=(1.63±0.16) MeV andT post=(1.14±0.26)MeV. The mean total kinetic energy of the fission fragments is TKE=(166±10) MeV and the measured width is σTKE=17.3MeV. The width of the fragment mass distribution is σ A =18.3u. The same reaction was analyzed using a modified statistical code which includes nuclear dissipation effects and particle and γ-ray emission in the equilibrium compound nucleus state an…
β decay of67Co
1999
The \ensuremath{\beta}-decay properties of ${}^{67}\mathrm{Co}$ produced in proton-induced fission of ${}^{238}\mathrm{U}$ were measured by the detection of \ensuremath{\beta}-delayed \ensuremath{\gamma} rays emitted from an isotopically pure mass-separated source obtained by laser ionization. The measured half-life of 0.425(20) s is more accurate than previous values. New \ensuremath{\gamma} transitions were observed, and corresponding branching ratios and $\mathrm{log}\mathrm{ft}$ values were deduced. The ${}^{67}\mathrm{Co}$ decay scheme is discussed in terms of the single-particle shell model.
First decay scheme of 113Tc and identification of 113Ru m
1998
Very neutron–rich fission products of the mass chain A=113 obtained from the IGISOL on–line mass separator have been investigated by γγ coincidence techniques and γ-spectra multiscaling. Gamma–rays following β–decay of 113Tc have been observed for the first time and a new 0.5 s isomeric state has been found in 113Ru.
STUDIES OF SUPERHEAVY ELEMENTS AT SHIP
2007
An overview of present experimental investigation of superheavy elements is given. The data are compared with theoretical descriptions. Results are reported from an experiment to confirm production of element 112 isotopes in irradiation of 238 UF 4 with 48 Ca . One spontaneous fission event was measured, which agrees with three events of previously measured data which had been assigned to the decay of 283112. However, more experimental work is needed in order to obtain an independent and unambiguous confirmation of previous results.
Miss Piggy, a californium-252 fission fragment source as a generator of short-lived radionuclides
2003
Abstract Carrier-free short-lived nuclides are employed in many different fields of modern nuclear chemistry. The two main production strategies are either thermal neutron-induced fission of 235U or 239Pu at nuclear reactors or spallation neutron sources or charged particle-induced nuclear reactions at accelerator facilities. An alternative method is to use a spontaneously fissioning nuclide. A facility applying this technique (“Miss Piggy”) was built at the University of Berne (Switzerland). Californium-252 (252Cf), which has a 3% fission branch and a half-life of 2.645 a, is used for the production of short-lived fission products that are stopped in an adjacent recoil chamber. Short-lived…
Evidence for intruder states in111Rh
1990
Levels in111Rh have been investigated via the γ -rays following the β−-decay of 2.1 s111Ru. The Ru activity was produced in the fission of249Cf and separated chemically from the fission product mixture. The emitted γ-rays were studied by γ singles and γ(t) coincidence measurements. Evidence for intruder states in111Rh has been obtained. Their properties are discussed and compared with those in the lighter Rh isotopes.
From Nuclear Fission to Superheavy Elements
1998
(1998). From Nuclear Fission to Superheavy Elements. Nuclear Physics News: Vol. 8, No. 2, pp. 7-21.