0000000000082905
AUTHOR
L. Stroe
Neutron yield from a thick target irradiated by 90MeV protons
In the context or the design of an intense source of low and intermediate energy, neutrons, the angular and energy distributions of neutrons produced in the interaction of 90 MeV protons in a C-12 target, in which the protons are stopped, have been measured by time-of-flight and activation techniques, As compared to C-12 the yield is less than a factor two higher, while it is somewhat less than for a Be-9 target. (c) 2005 Elsevier B.V. All rights reserved.
Neutron yields from a thick 13C target irradiated by 30 MeV protons
Abstract Total neutron yields resulting from the proton bombardment of a thick 13 C target have been measured for 30 MeV protons. Absolute intensities, angular distributions and energy spectra of neutrons have been obtained by the time-of-flight technique where the detectors provided continuous coverage from 0° to 120°. Resonances have been found, some of which can be attributed to known states in 14 N. A total yield of 0.022(3) n/p was observed with a slight angular anisotropy towards forward angles. The measured yields are compared to the neutron yields produced by using deuterons on thick 12 C and 9 Be targets.
Yields of neutron-rich rubidium and cesium isotopes from fast-neutron induced fission of 238U, obtained by studying their release from a thick ISOL target
Abstract In the framework of the EURISOL project, the production of neutron-rich isotopes of rubidium and cesium has been studied. The intensities of mass-separated beams of rubidium and cesium isotopes generated from a thick 238 UC x target connected to a surface ionizer have been measured. The release properties of 140 Cs and 91 Rb have been investigated. The obtained results allowed us to determine the relative fission yields of rubidium and cesium isotopes with high accuracy.
Electromagnetic transition rates in theN=80nucleus58138Ce
The half-life of the Iπ=6+ yrast state at Ex=2294 keV in 138Ce has been measured as T1/2=880(19) ps using the fast-timing γ-ray coincidence method with a mixed LaBr3(Ce)-HPGe array. The excited states in 138Ce have been populated by the 130Te(12C,4n) fusion-evaporation reaction at an incident beam energy of 56 MeV. The extracted B(E2;61+→41+)=0.101(24) W.u. value is compared with the predictions of truncated basis shell model calculations and with the systematics of the region. This shows an anomalous behavior compared to the neighboring isotonic and isotopic chains. Half-lives for the yrast 5-, 11+ and 14+ states in 138Ce have also been determined in this work.
Production of neutron-rich nuclei in fission induced by neutrons generated by the p + 13C reaction at 55 MeV
Cross-sections for the production of neutron-rich nuclei obtained by neutron-induced fission of natural uranium have been measured. The neutrons were generated by bombarding a 13C target with 55 MeV protons. The results, position of the maximum in the (Z, A)-plane, width and magnitude, are very comparable with those where the neutrons are generated by bombardment of natural 12C graphite with 50 MeV deuterons. Depending on the geometry of the converter/target assembly the isotope yields, however, are a factor of 2-3 lower due to less efficient production of neutrons per primary projectile, especially at small forward angles.
Precision Lifetime Measurements Using LaBr3 Detectors With Stable and Radioactive Beams
A range of high resolution gamma-ray spectroscopy measurements have been carried out using arrays which include a number of Cerium-doped Lanthanum-Tribromide (LrBr3 (Ce)) scintillation detectors used in conjunction with high-resolution hyper-pure germanium detectors. Examples of the spectral and temporal responses of such set-ups, using both standard point radioactive sources 152 Eu and 56 Co, and in-beam fusionevaporation reaction experiments for precision measurements of nuclear excited states in 34 P and 138 Ce are presented. The current and future use of such arrays at existing (EURICA at RIKEN) and future (NUSTAR at FAIR) secondary radioactive beam facilities for precision measurements…
Electromagnetic Transition Rate Measurements in theN=80 Isotone,138Ce
A study of intrinsic state halflife measurements in the N=80 nucleus 138Ce has been made using the 130Te(12C,4n)138Ce fusion evaporation reaction at beam energy of 56 MeV. The fast-timing gamma-ray coincidence method was used with a mixed LaBr3(Ce)-HPGe array to establish the lifetimes of the yrast 6+ state at 2294 keV, the Iπ=5− state at 2218 keV, the Iπ=11+ state at 3943 keV and the 14+ state at that at 5312 keV, all of which are in the sub nanosecond regime. Reduced transition probabilities have been calculated for the electromagnetic decays from these states.
Production of neutron-rich surface-ionized nuclides at PARRNe
Yields of neutron-rich isotopes produced by fast neutron induced fission of 238 U were measured at the ISOL set-up Production dAtomes Radioactifs Riches en Neutrons. A surface ion source was used to ionize selectively elements with low ionization potentials. In order to observe also the most n-rich isotopes, the identification was achieved by a combined measurement of b- and c-rays and b-delayed neutrons. The flux of fast neutrons inducing fission was generated by a 1 lA beam of 26 MeV deuterons stopped in a graphite converter. The target was a standard ISOLDE type 238 UC