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Rasco, Bertis C.

Publications and source records attributed to Rasco, Bertis C..

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Probing Optimal Reaction Energy for Synthesis of Element 119 from 51 V+ 248 Cm Reaction with Quasielastic Barrier Distribution Measurement

Here, the quasielastic barrier distribution of 51 V+ 248 Cm was extracted by measuring the excitation function of quasielastic backscattering using a gas-filled recoil ion separator, GARIS-III. The obtained barrier distribution is well explained by the coupled-channels calculation, indicating a significant effect of the rotational excitation of deformed 248 Cm. From the measured average Coulomb barrier height and deformation parameters of 248 Cm, the side-collision energy leading to a compact configuration of colliding nuclei was obtained. The relation between the side collision energy and the excitation function of the evaporation-residue cross sections in the 48 Ca+ 248 Cm system was evaluated as a reference for the 51 V+ 248 Cm case. The optimal reaction energy to synthesize a new element 119 at the 51 V+ 248 Cm fusion reaction (3n and 4n channels) was estimated with an aid of these experimental data.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

New γ -ray transitions observed in Ne 19 with implications for the O 15 ( α , γ ) Ne 19 reaction rate

The 15 O(α,γ) 19 Ne reaction is responsible for breakout from the hot CNO cycle in type I x-ray bursts. Understanding the properties of resonances between E x =4 and 5 MeV in 19 Ne is crucial in the calculation of this reaction rate. The spins and parities of these states are well known, with the exception of the 4.14- and 4.20-MeV states, which have adopted spin-parities of 9/2 - and 7/2 - , respectively. γ-ray transitions from these states were studied using triton-γ – γ coincidences from the 19 F( 3 He,tγ) 19 Ne reaction measured with the GODDESS (Gammasphere ORRUBA Dual Detectors for Experimental Structure Studies) at Argonne National Laboratory. The observed transitions from the 4.14- and 4.20-MeV states provide strong evidence that the J π values are actually 7/2 - and 9/2 - , respectively. These assignments are consistent with the values in the 19 F mirror nucleus and in contrast to previously accepted assignments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

The ORNL analysis technique for extracting β -delayed multi-neutron branching ratios with BRIKEN

Here, many choices are available in order to evaluate large radioactive decay networks. There are many parameters that influence the calculated -decay delayed single and multi-neutron emission branching fractions. We describe assumptions about the decay model, background, and other parameters and their influence on β-decay delayed multi-neutron emission analysis. An analysis technique, the ORNL BRIKEN analysis procedure, for determining -delayed multi-neutron branching ratios in β-neutron precursors produced by means of heavy-ion fragmentation is presented. The technique is based on estimating the initial activities of zero, one, and two neutrons occurring in coincidence with an ion-implant and β trigger. The technique allows one to extract β-delayed multi-neutron decay branching ratios measured with the 3 He BRIKEN neutron counter. As an example, two analyses of the -neutron emitter 77 Cu based on different a priori assumptions are presented along with comparisons to literature values.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Updated β -decay measurement of neutron-rich Cu 74

Here, the β decay of neutron-rich 74 Cu has been studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. By using a high-resolution mass separator a purified 74 Cu beam was obtained, thus allowing decay through its isobar chain to stable 74 Ge without any decay chain member dominating. A total of 170γ rays were associated with 74 Cuβ decay with 111 placed in the 74 Zn level scheme. Updated β feeding intensities and estimated log(ft) values are presented, and new J π assignments are proposed using shell model calculations. The progression of simulated total absorption γ-ray spectroscopy (TAGS) based on proposed levels and β-feeding values from previous measurements to this evaluation are presented and demonstrate the need for a TAGS measurements for this and similar decays.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Impact of Modular Total Absorption Spectrometer measurements of β decay of fission products on the decay heat and reactor ν ¯ e flux calculation

Here, we report the results of a β-decay study of fission products 86 Br, 89 Kr, 89 Rb, 90 gs Rb, 90m Rb, 90 Kr, 92 Rb, 139 Xe, and 142 Cs performed with the Modular Total Absorption Spectrometer (MTAS) and on-line mass-separated ion beams. These radioactivities were assessed by the Nuclear Energy Agency as having high priority for decay heat analysis during a nuclear fuel cycle. We observe a substantial increase in β feeding to high excited states in all daughter isotopes in comparison to earlier data. This increases the average γ-ray energy emitted by the decay of fission fragments during the first 10 000 s after fission of 235 U and 239 Pu by approximately 2% and 1%, respectively, improving agreement between results of calculations and direct observations. New MTAS results reduce the reference reactor ¯ν e flux used to analyze reactor ¯ν e interaction with detector matter. The reduction determined by the ab initio method for the four nuclear fuel components, 235 U, 238 U, 239 Pu, and 241 Pu, amounts to 0.976, 0.986, 0.983, and 0.984, respectively.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

$\beta $ Decays of $^{92}$Rb, $^{96\mathrm {gs}}$Y, and $^{142}$Cs Measured with the Modular Total Absorption Spectrometer and the Influence of $\gamma $ Multiplicity on Total Absorption Spectrometry Measurements

Total absorption spectroscopy is a technique that helps obtain reliable β-feeding patterns of complex decays important for nuclear structure and astrophysics modeling as well as decay heat analysis in nuclear reactors. The need for improved measurements of β-feeding patterns from fission decay products has come to the forefront of experiments that use nuclear reactors as a source of antineutrinos. Furthermore we present more detailed results, in particular the β-decay measurements of 96gs Y, and demonstrate the impact of the β-delayed γ multiplicity on the overall efficiency of Modular Total Absorption Spectrometer used at Oak Ridge National Laboratory to study the decays of fission products abundant during a nuclear fuel cycle.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Modular total absorption spectrometer

The design and performance of the Modular Total Absorption Spectrometer built and commissioned at the Oak Ridge National Laboratory is presented here. The active volume of the detector is approximately one ton of NaI(Tl), which results in very high full γ energy peak efficiency of 71% at 6 MeV and nearly flat efficiency of around 81.5% for low energy γ-rays between 300 keV and 1 MeV. In addition to the high peak efficiency, the modular construction of the detector permits the use of a γ-coincidence technique in data analysis as well as β-delayed neutron observation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗