Search results for "fission products"

Decay of the heaviest isotope of neodymium:154Nd

1985

The neutron-rich isotope154Nd has been separated from235U fission products with the HELIum-jet On-line mass Separator HELIOS and investigated by γ-singles, γγ- and γX-coincidence measurements. The Z- and A-assignment have been confirmed by the observation of promethium KX-rays and by the genetic relationship to the daughter product 1.7-min154Pm. A half-life of 26±2 s has been obtained for154Nd, and a partial decay scheme is proposed. A 40 s activity previously assigned to154Nd could not be confirmed.

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.

The collective structure of106,108Ru

1984

Levels in106,108Ru have been studied by measuringγγ coincidences andγγ directional correlations of theγ-rays following theβ−-decay of 36 s106Tc and 5 s108Tc. Tc activities were separated chemically from the fission products of thermal neutron induced fission of239Pu by the continuously running system “SISAK 2” and theγ-radiation was measured on-line. An extended level scheme for108Ru, spin assignments,E2/M1 multipole mixing ratios andB(E2) ratios for106Ru and108Ru have been obtained. The collective structure of the two nuclei is discussed in the framework of different nuclear models.

Neutron-rich nuclei and fission; recent developments and future aspects

2002

Production and studies of neutron-rich nuclei produced in fission are reviewed. Some recent experiments performed with the ISOL technique at the IGISOL and the ISOLDE facilities are reviewed. The manipulation of neutron-rich nuclei is discussed with a special focus on radioactive ion cooling and trapping techniques under construction worldwide. Perspectives of obtaining intense post accelarated beams of fission products are discussed.

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.

Simulations of the stopping efficiencies of fission ion guides

2017

With the Ion Guide Isotope Separator On-Line (IGISOL) facility, located at the University of Jyväskylä, products of nuclear reactions are separated by mass. The high resolving power of the JYFLTRAP Penning trap, with full separation of individual nuclides, capacitates the study of nuclides far from the line of stability. For the production of neutron-rich medium-heavy nuclides, fissioning of actinides is a feasible reaction. This can be achieved with protons from an in-house accelerator or, alternatively, with neutrons through the addition of a newly developed Be(p,xn)-converter. The hereby-obtained fission products are used in nuclear data measurements, for example fission yields, nuclear …

Fission yield measurements at IGISOL

2016

The fission product yields are an important characteristic of the fission process. In fundamental physics, knowledge of the yield distributions is needed to better understand the fission process. For nuclear energy applications good knowledge of neutroninduced fission-product yields is important for the safe and efficient operation of nuclear power plants. With the Ion Guide Isotope Separator On-Line (IGISOL) technique, products of nuclear reactions are stopped in a buffer gas and then extracted and separated by mass. Thanks to the high resolving power of the JYFLTRAP Penning trap, at University of Jyväskylä, fission products can be isobarically separated, making it possible to measure rela…

2020

The novel technology of calorimetric low-temperature detectors (CLTDs) was applied to determine isotopic yields of fission fragments using the passive absorber method for thermal-neutron-induced fission reactions at the LOHENGRIN mass spectrometer at the Institut Laue-Langevin in Grenoble, France. Precise yields were determined for $^{92}\mathrm{Rb}$ and $^{96}\mathrm{Y}$. These fission products are the dominant contributors to the high-energy portion of the reactor antineutrino spectra. Our new measurements resolve inconsistencies between previous yield measurements and fission data libraries and reduce the nuclear data uncertainties in the computation of reactor antineutrino spectra by th…

Production of Sn and Sb isotopes in high-energy neutron induced fission of natU

2018

The first systematic measurement of neutron-induced fission yields has been performed at the upgraded IGISOL-4 facility at the University of Jyväskylä, Finland. The fission products from high-energy neutron-induced fission of nat U were stopped in a gas cell filled with helium buffer gas, and were online separated with a dipole magnet. The isobars, with masses in the range A = 128-133 , were transported to a tape-implantation station and identified using γ -spectroscopy. We report here the relative cumulative isotopic yields of tin (Z = 50) and the relative independent isotopic yields of antimony (Z = 51). Isomeric yield ratios were also obtained for five nuclides. The yields of tin show a …