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Temanson, E.

Publications and source records attributed to Temanson, E..

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Single-neutron adding on $^{34}$S

For this work, single-neutron adding data was collected in order to determine the distribution of the single-neutron strength of the 0Ζ’ 7/2 , 1p 3/2 , 1p 1/2 and 0Ζ’ 5/2 orbitals outside of Z = 16, N = 18, 34 S. The 34 S(d,p) 35 S reaction has been measured at 8 MeV/u to investigate cross sections to excited states in 35 S. Outgoing proton yields and momenta were analyzed by the Super-Enge Split-Pole Spectrograph in conjunction with the CeBrA demonstrator located at the John D. Fox Laboratory at Florida State University. Angular distributions were compared with Distorted Wave Born Approximation calculations in order to extract single-neutron spectroscopic overlaps. Spectroscopic overlaps and strengths were determined for states in S up through 6 MeV in excitation energy. Each orbital was observed to have fragmented strength where a single level carried the majority. The single-neutron centroids of the 0Ζ’ 7/2 , 1p 3/2 , 1p 1/2 and 0Ζ’ 5/2 orbitals were determined to be 2360$^{+90}_{-40}$ keV, 3280$^{+80}_{-50}$ keV, 4780$^{+60}_{-40}$ keV, and ≳7500 keV, respectively. A previous discrepancy in the literature with respect to the distribution of the neutron 1p 1/2 strength was resolved. The integration of the normalized spectroscopic strengths, up to 5.1 MeV in excitation energy, revealed fully-vacant occupancies for the 0Ζ’ 7/2 , 1p 3/2 , and 1p 1/2 orbitals, as expected. The spacing in the single-neutron energies highlighted a reduction in the traditional N = 28 shell-gap, relative to both the 1p spin-orbit energy difference (N = 32) and the lower limit on the N = 34 shell spacing.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Suppressed electric quadrupole collectivity in 49 Ti

Single-step Coulomb excitation of 46,48,49,50 Ti is presented. A complete set of E2 matrix elements for the quintuplet of states in 49 Ti, centred on the core excitation, was measured for the first time. A total of nine E2 matrix elements are reported, four of which were previously unknown. $^{49}_{22}$Ti 27 shows a 20% quenching in electric quadrupole transition strength as compared to its semi-magic $^{50}_{22}$Ti 28 neighbour. This 20% quenching, while empirically unprecedented, can be explained with a remarkably simple two-state mixing model, which is also consistent with other ground-state properties such as the magnetic dipole moment and electric quadrupole moment. A connection to nucleon transfer data and the quenching of single-particle strength is also demonstrated. The simplicity of the 49 Ti- 50 Ti pair (i.e., approximate single-j 0 7/2 valence space and isolation of yrast states from non-yrast states) provides a unique opportunity to disentangle otherwise competing effects in the ground-state properties of atomic nuclei, the emergence of collectivity, and the role of proton-neutron interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Measurement of the 25 Al(𝑑,𝑛)⁒ 26 Si reaction and impact on the 25 Al⁒(𝑝,𝛾)⁒ 26 Si reaction rate

The 25 Al(p,Ξ³) 26 Si reaction plays a key role in nucleosynthesis pathways that influence the galactic abundance of 26 Al. A more precise determination of the proton strength of the lowest β„“ = 0 proton resonance in 26 Si is needed to improve reaction-rate calculations. This work measures the 25 Al(d,n) 26 Si proton-transfer reaction in inverse kinematics using a radioactive ion beam at RESOLUT, determining excitation energies and cross sections for the lowest β„“ = 0 resonance associated with the 3 + 3 state at 5.92(2) MeV. Coupled-reaction-channels calculations (FRESCO) are used to extract the β„“ = 0 spectroscopic factor and the corresponding proton width, yielding Ξ“β‚š = 2.19(45) eV and a (p,Ξ³) resonance strength of 26(10) meV. This resonance is found to dominate the 25 Al(p,Ξ³) 26 Si reaction rate above 0.2 GK.

20 ≀ A ≀ 38β†—
DOE OSTI2023

The CeBrA demonstrator for particle-Ξ³ coincidence experiments at the FSU Super-Enge Split-Pole Spectrograph

We report on a highly selective experimental setup for particle-Ξ³ coincidence experiments at the Super-Enge Split-Pole Spectrograph (SE-SPS) of the John D. Fox Superconducting Linear Accelerator Laboratory at Florida State University (FSU) using fast CeBr scintillators for Ξ³-ray detection. Specifically, we report on the results of characterization tests for the first five CeBr 3 scintillation detectors of the CeBr 3 Array (CeBrA) with respect to energy resolution and timing characteristics. We also present results from the first particle-Ξ³ coincidence experiments successfully performed with the CeBrA demonstrator and the FSU SE-SPS. We show that with the new setup, Ξ³-decay branching ratios and particle-Ξ³ angular correlations can be measured very selectively using narrow excitation energy gates, which are possible thanks to the excellent particle energy resolution of the SE-SPS. In addition, we highlight that nuclear level lifetimes in the nanoseconds regime can be determined by measuring the time difference between particle detection with the SE-SPS focal-plane scintillator and Ξ³-ray detection with the fast CeBrA detectors. As a result, selective excitation energy gates with the SE-SPS exclude any feeding contributions to these lifetimes.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND β†—
DOE OSTI2022

Lifetime measurements of 0 + states in Er 168 with the Doppler-shift attenuation method

Here, the lowest-lying shape oscillations of deformed nuclei have been described as quadrupole in nature (Ξ» = 2), resulting in two types of vibrations or oscillations: Ξ² vibrations with oscillations along the symmetry axis (K Ο€ = 0 + ) and Ξ³ vibrations breaking axial symmetry with a projection of K Ο€ = 2 + on the symmetry axis. The Ξ³ vibration seems to be well characterized as the first K Ο€ = $2^+_1$ (or $2^+_Ξ³$) band in deformed nuclei and exhibits a systematic behavior across the region. The nature of the K Ο€ = 0 + excitations, however, has remained poorly understood and has been open to debate for some decades. The goal of this work is to understand the nature of 0 + states observed in 168 Er through measurements of the lifetimes of these states and to determine if they are consistent with oscillations built on a deformed ground state, the minima of other coexisting shapes, single-particle states, or a mixture of effects. Lifetimes of excited states in the 168 Er nucleus were measured with the Doppler Shift Attenuation Method (DSAM) and the inelastic neutron scattering reaction, (n, n'Ξ³), at the University of Kentucky Accelerator Laboratory. Numerous 0 + states had been observed by the (p, t) reaction. We confirm the 0 + states at 1217.2, 1421.5, 1833.6, 2364.9, 2392.1, and 2643.0 keV in 168 Er. We could not, however, support the previous assignments of 0 + levels at 2114.1, 2200.6, 2572.5, and 2617.4 keV. We report measured lifetimes for six confirmed 0 + excitations and additional members of 0 + bands. The results for 168 Er show that it is the third excited K Ο€ = 0 + ($0^+_4$) excitation that carries the collective strength and, therefore, the potential to be an oscillation on the ground state. This result is similar to the case in 166 Er, where it was also the $0^+_4$ state that exhibited greater collectivity than the first excited K Ο€ = 0 + band. The Delaroche et al. prediction for a collective K Ο€ = 0 + band is at E T =1.818 MeV which corresponds the third excited K Ο€ = 0 + band.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Toward Measuring Prompt Fission Products in Coincidence

Despite the discovery of fission nearly 80 years ago and its importance to nuclear energy, national security, and astrophysics, there are very few measurements of the correlations between multiple fission products. An experiment is underway at Oak Ridge National Laboratory to measure the energy and angle correlations between prompt fission neutrons, Ξ³ rays, and fragments. These measurements could reveal the existence of scission neutrons, the energy balance between these products, and other details needed for benchmarking advanced fission models. The setup includes an array of VANDLE neutron detectors and a Ξ³-ray detector positioned opposite a suite of detectors to determine the mass of one fragment. Preliminary results with a spontaneous 252Cf source show expected correlations between prompt fragments and neutrons along the fission axis. Further refinements will improve the resolution of the fragment mass and increase efficiency for triple-coincident events. Future experiments could be done with a neutron beam to study induced fission on thin targets.

Peters, William A.β†—