0000000000383051
AUTHOR
C. Ristori
Half-lives andP n values of delayed-neutron precursors in the mass chains 85?87, 92, 135, 136 and 145
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…
Beta-delayed neutron emission from93?100Rb to excited states in the residual Sr isotopes
Beta-delayed neutron emission from the precursors93–100Rb to excited states in the residual nuclei92–99Sr has been measured by means ofγ-ray and neutron spectroscopy. In general, considerable neutron feeding of excited final states is observed. The experimental branching ratios (P ) are compared to predictions from statistical model calculations. It is demonstrated that the main parameter affecting theP -values is the shape of theβ-strength function (S β). For several Rb isotopes hindrance, respectively enhancement of neutron branches to specific final states is observed giving evidence for the persistence of intermediate structure of the neutron-emitting states. By the example of98Rb it is…
Half-lives and delayed neutron emission probabilities of short-lived Rb and Cs precursors
Half-lives and delayed-neutron emission probabilities (P n ) of short-lived Rb and Cs precursors in the mass chains 94–98 and 143–147 were measured. Sources of isotope separated nuclides were obtained from the on-line mass-separator OSTIS installed at the Grenoble high-flux reactor.
Beta-delayed neutrons and high-energy gamma-rays from decay of137I
Beta-delayed neutrons and high-energyγ-rays following decay of137I have been studied in order to characterizeβ-decay to and deexcitation of neutron-unbound levels in137Xe. The totalγ-ray intensity observed accounts for at least 20% of theβ-intensity to levels aboveB n . No evidence was found for neutron andγ-ray emission from the same levels. With the experimentalβ-strength function aboveB n detailed tests were performed on the reproduction of the experimental neutron spectrum, the level density and Porter-Thomas fluctuations of the reducedβ-transition probabilities to highly excited states in137Xe.