Search results for "Fission"

Half-lives andP n values of delayed-neutron precursors in the mass chains 85?87, 92, 135, 136 and 145

1978

Further results are presented on half-lives and neutron emission probabilities (P n ) of short-lived delayed-neutron precursors in the mass chains 85–87, 92, 135, 136 and 145 obtained with the recoil focussing parabola-type mass separator for unslowed fission products LOHENGRIN installed at the Grenoble high-flux reactor. A newP n -value of (44±14)% is given for the (0.73±0.06)s87As; theP n -values of seven precursor nuclides have been redetermined: (1.9±0.1)s85As with (22±8)%, 0.9s86As with (10.5±2.2)%, (0.35±0.04)s92Br with (21±8)%, (1.6±0.15)s135Sb with (14±1)%, (0.9±0.1)s136Sb with (19±9)%, (17.5±0.2)s136Te with (2.0±1.0)% and 0.6s145Cs with (12.5±3.0)%. The results are compared with th…

Intruder states in even-even neutron-rich Pd isotopes

1998

The decays of 112Rh g and 112Rh m obtained as on-line mass separated fission products have been investigated by standard β and γ spectroscopic techniques and γ-γ angular correlations. Low-lying 0+ and 2+ states are identified in the daughter nucleus 112Pd. Systematics suggests the existence of an intruder band which is the lowest in 110Pd, i.e. two neutrons before the midshell.

Neutron and gamma-ray emission in the proton induced fission of 238U and 242Pu

2004

Abstract Average prescission Mpren and postscission Mpostn neutron multiplicities as well as average γ-ray multiplicity 〈Mγ〉, average energy 〈Eγ〉 emitted by γ-rays as a function of mass and total kinetic energy (TKE) of fission fragments were measured in proton induced reactions p+ 242 Pu→ 243 Am , p+ 238 U→ 239 Np at proton energy Ep=13, 20 and 55 MeV.

Properties of heavy nuclei measured at the GSI SHIP

2004

Abstract The nuclear shell model predicts that the next doubly magic shell-closure beyond 208 Pb is at a proton number Z = 114, 120, or 126 and at a neutron number N = 172 or 184. The outstanding aim of experimental investigations is the exploration of this region of spherical ‘Super-Heavy Elements’ (SHEs). The measured decay data reveal that for the heaviest elements, the dominant decay mode is α emission, not fission. Decay properties as well as reaction cross-sections are compared with results of theoretical investigations. Finally, plans are presented for the further development of the experimental set-up and the application of new techniques.At a higher sensitivity, the exploration of …

Unusual excitation-energy division in quasi-fission reactions between50Ti,54Cr and58Fe with207,208Pb at the barrier

1987

Beta decay energies and nuclear masses of148Ba,148La and151Pr

1990

Theβ-decay energy of the neutron-rich isotopes148Ba,148La and151Pr has been measured at the Institute Laue-Langevin (ILL). The148Ba- and148La-nuclei were produced using a high-temperature ion source at the OSTIS separator of this institute, whereas samples of151Pr were obtained from the thermal fission of239Pu, used as a target in the mass separator LOHENGRIN. At both instruments,βγ-coincidences were measured with a plastic scintillator telescope and a Ge(I)-detector, together withβ-singles andγ-singles spectra. Theβ-spectra emitted in coincidence with 44γ-lines in the decay of these nuclei have been evaluated. From their endpoint energies, the followingQβ-values have been obtained:Qβ(148Ba…

β-delayed fission of186,188Bi isotopes

2013

By using the technique of correlating implanted evaporation residues and their subsequent fission decay, $\ensuremath{\beta}$-delayed fission ($\ensuremath{\beta}$DF) of ${}^{186}$Bi has been identified for the first time and $\ensuremath{\beta}$DF of ${}^{188}$Bi has been unambiguously confirmed. The experiments were performed at the velocity filter SHIP (GSI, Darmstadt). The $\ensuremath{\beta}$DF probabilities for both nuclides were qualitatively estimated, and, in particular indications for a large value in the case of ${}^{186}$Bi are regarded.

Energy and range focusing of in-flight separated exotic nuclei – A study for the energy-buncher stage of the low-energy branch of the Super-FRS

2003

Abstract The relative momentum spread of in-flight separated exotic nuclear beams produced in fragmentation and/or fission reactions is of the order of a few percent. A new technique is presented, which reduces the momentum spread significantly, and first experimental results obtained with relativistic projectile fragments are shown. This technique is the key to experiments with slowed-down and stopped beams, in particular for the efficient stopping of relativistic exotic nuclei in gas-filled stopping cells. It will be employed at the energy-buncher stage of the low-energy branch of the Super-FRS facility. The ion-optical design of the energy buncher is presented and a brief outlook to the …

Manifestation of fine structures in the fission fragment mass-energy distribution of the reaction

2002

Methods of identifying structure peculiarities in two-dimensional distributions of experimental observables are discussed. Structures different from that produced by proton odd-even staggering were revealed for the first time in the mass-energy distribution of fission fragments in the 233 Uðnth; fÞ reaction. The new structures could presumably be linked with fission modes and collective vibrations of the fissioning system. r 2002 Elsevier Science B.V. All rights reserved.

Toward large-area targets for “TRAKULA”

2011

Abstract TRAKULA ( Tra nsmutationsrelevante k ernphysikalische U ntersuchungen l anglebiger A ktinide, i.e., nuclear physical investigations of long-lived actinides with relevance to transmutation) is a joint research project of the German Federal Ministry of Science and Education (BMBF) on nuclear physics investigations with modern scientific, technological and numerical methods. Experiments concerning the transmutation of radioactive waste are a central topic of the project. For this, large-area samples (≥40 cm 2 ) of 235,238 U and 239,242 Pu compounds are required for the calibration of fission chambers and for fission yield measurements. Another topic within the project requires large-a…