Search results for " Yield"
showing 10 items of 550 documents
Developments for neutron-induced fission at IGISOL-4
2016
At the IGISOL-4 facility, neutron-rich, medium mass nuclei have usually been produced via charged particle-induced fission of natural uranium and thorium. Neutron-induced fission is expected to have a higher production cross section of the most neutron-rich species. Development of a neutron source along with a new ion guide continues to be one of the major goals since the commissioning of IGISOL-4. Neutron intensities at di↵erent angles from a beryllium neutron source have been measured in an on-line experiment with a 30 MeV proton beam. Recently, the new ion guide coupled to the neutron source has been tested as well. Details of the neutron source and ion guide design together with prelimi…
Delayed-neutrons from arsenic isotopes 84As, 85As and 86As
1973
Abstract Short-lived arsenic isotopes were produced by thermal-neutron fission of 235U and isolated within 2·5 sec by volatilization of arsenic hydride. The existence of a strong delayed-neutron precursor of 2·05±0·05 sec half-life among the arsenic isotopes is confirmed and its assignment to 85As ascertained by milking of the daughter product 33 sec 85Se and 3·1 min 84Se, which is the final nucleus in the neutron decay branch of 85As. A delayed-neutron yield of 7·8 ± 1·2 neutrons/104 fissions was obtained for 85As. A new isotope, 0·9 ± 0·2 sec 86As, was detected by delayed-neutron counting and by following the decay of its most prominent γ-ray. The mass assignment was verified by milking o…
Fission product yields at intermediate energy
1998
The results of experimental and theoretical studies of fission product yields in proton-induced fission of 238U are presented. The yields of neutron-rich Ni, Cu, Zn, Ga and Ge—isotopes were measured by 25 MeV protons and the ion guide-based isotope separator technique. The pre-neutron emission fragment mass distributions were measured by protons at energies Ep=20, 35, 50 and 60 MeV using time-of-flight method. The results indicate enhancement for superasymmetric mass division at intermediate excitation energy of the fissioning nucleus. A model calculation of fission products yields for fission of 238U by protons and neutrons is presented which predicts the formation cross sections for neutr…
Mass and charge distributions in the very asymmetric thermal neutron induced fission of the odd-Z nucleus 242mAm
1999
Yields of light fission products (A = 68, 70-84, 87, 88, 94, 96, 98, 102 and 106-108), their kinetic energies and nuclear charge distributions (A = 71-84, 87 and 88) in the thermal neutron induced fission of the odd-Z nucleus Am-242m(Z = 95) were measured using the mass-separator Lohengrin at the Institute Laue-Langevin in Grenoble (France). The mass yield curve shows a fine structure at A = 70, probably due to shell and/or odd-even effects affecting also the nuclear charge distribution. The analysis of isotopic chain yields gives evidence for a very low excitation energy of the lightest fission fragments observed. A preferential formation of fragments with even Z is found for this odd-Z co…
New model and code for calculation of product yields in fusion-fission reactions
2003
A new version of the theoretical model and computing code for calculations of the pre- and post-scission light particle spectra and multiplicity distributions, the evaporation residue cross sections, and the fission product yield cross sections has been developed. The most important dynamical effects (nuclear friction and light particle emission at the descent from saddle to scission point) in the decay of heated rotating compound nuclei were included in consideration [1]. The fission characteristics have been calculated for every compound nucleus at excitation energy and angular momentum at the scission point. The contributions from different fission modes including the superasymmetric one…
Superasymmetric fission at intermediate energy and production of neutron-rich nuclei with A < 80
1997
Abstract The yields of neutron-rich Ni, Cu, Zn, Ga and Ge-isotopes were measured in 25 MeV proton induced fission of 238 U using the ion guide-based isotope separator technique. The results indicate enhancement for superasymmetric mass division at intermediate excitation energy of the fissioning nucleus and show the potential of this reaction for the production of neutron-rich exotic nuclei around Z = 28.
Levels in104Ru populated by the ??-decay of104Tc
1978
Theβ− — andγ-activities of 18.4 min104Tc have been studied with singles and coincidence measurements. Sources were prepared by chemical separation of technetium from the fission products of thermal-neutron-induced fission of235U. A revised level scheme of104Ru up to an excitation energy of 4.26 MeV is proposed. Fromβ-γ coincidence measurements, aQβ-value of 5.62±0.07 MeV has been obtained.
A study of fusion - fission atZ= 107
1997
An experiment was performed with the EUROGAM II array to investigate the reaction channels that are open in the fusion of a beam on the actinide target at a series of energies around the Coulomb barrier. The symmetric fission products identified from the level structures seem to suggest that a proton and neutrons are emitted prior to 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…
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…