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Hanselman, K.

Publications and source records attributed to Hanselman, K..

10 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 OSTI2024

Measurement of g 9/2 strength in the stretched 8 – state and other negative parity states via the 51 V (d,p) 52 V reaction

We performed a measurement of the 51 V (d,p) 52 V reaction at 16 MeV using the Florida State University Super-Enge Split-Pole Spectrograph (SE-SPS) to search for single-neutron transfer strength for the g 9/2 intruder orbit. Measurements of Ξ½g 9/2 strength with (d, p) reactions in the N = 29 isotones 49 Ca, 51 Ti, 53 Cr, and 55 Fe have concluded that much of the expected Ξ½g 9/2 strength is β€œmissing”; that is, the summed strength is much smaller than the sum rule. In odd-odd N = 29 isotones, we expect a significant amount of Ξ½g 9/2 strength to be located in the β€œstretched” 8 – states with Ο€ $f$$^{n}_{7/2}$Ξ½g 9/2 structure that were systematically observed in the odd-odd N = 29 isotones via the (Ξ±,d) reaction. 52 V is the only one of these odd-odd isotones in which a stable target is available for single-neutron transfer reactions. We report on a determination of Ξ½g 9/2 strength for the stretched 8 – state and ten other negative parity states populated via L = 4 transfer in the 51 V(d, p) 52 V reaction. Furthermore, this is the first measurement of spectroscopic strength for L = 4 states in 52 V via (d, p). In total, the L = 4 strength observed here sums to only 28.9(11)% of the sum rule for g 9/2 neutron strength, a result that is consistent with the summed strengths observed in recent (d, p) measurements of the even-Z N = 29 isotones 51 Ti, 53 Cr, and 55 Fe. The (Ξ±,3 He) reaction and the use of particle-Ξ³ coincidences would provide more sensitivity to search for the missing g 9/2 strength.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
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 OSTI2023

g 9/2 neutron strength in the N = 29 isotones and the 52 Cr(d,p)⁒ 53 Cr reaction

We performed a measurement of the 52 Cr(d,p)⁒⁒ 53 Cr reaction at 16 MeV using the Florida State University Super-Enge Split-Pole Spectrograph (SE-SPS) and observed 26 states. While all of the states observed here had been seen in previous (d,p) experiments, we changed five L assignments from those reported previously and determined L values for nine states that had not had such assignments made previously. The g 9/2 neutron strength observed in 53 Cr in the present work and in the N = 29 isotones 49 Ca, 51 Ti, and 55 Fe via (d,p) reactions is much smaller than the sum rule for this strength. Most of the observed L = 4 strength in these nuclei is located in states near 4 MeV excitation energy. The remaining g 9/2 strength may be located in the continuum or may be fragmented among many bound states. A covariant density-functional theory calculation provides support for the hypothesis that the g 9/2 neutron orbit is unbound in 53 Cr. The (α, 3 He) reaction may provide a more sensitive probe for the missing g 9/2 neutron strength. Additionally, particle-γ coincidence experiments may help resolve some remaining questions in this nucleus.

39 ≀ A ≀ 58β†—
DOE OSTI2022

Observation of a Near-Threshold Proton Resonance in 11 B

A near-threshold proton resonance in 11 B at 𝐸 ex = 11.44 Β± 0.04 MeV is observed via the reaction 10 Be⁒(𝑑,𝑛)⁒ 11 B β†’ 10 Be + 𝑝 in inverse kinematics, measured with a beam of the radioactive isotope 10 Be. The resonance energy at 𝐸 res = 211⁒(40) keV is consistent with a proton signal observed by Ayyad et al. in the 𝛽-delayed proton decay of 11 Be. By comparison to a distorted wave Born approximation calculation, a 0.27(6) spectroscopic factor is extracted and a tentative (β„“ = 0) character is assigned for this resonance. The significant cross section in the proton-transfer (𝑑,𝑛) reaction, as well as the observation of its proton-decay signal, point to the threshold-resonance character of this state. The position of this state, its structure, and strong coupling to the 𝑠-wave continuum represent an ideal case to study quantum near-threshold many-body dynamics of unstable states. In conclusion, the presence of this state is an important step toward understanding the excessively large beta-delayed proton-decay branch of 11 Be.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Characterization of the CATRiNA neutron detector system

The Compound Array for Transfer Reactions in Nuclear Astrophysics (CATRiNA) is a neutron detector system which has been developed at Florida State University to measure neutrons from nuclear reactions aimed to help in the understanding of the structure of the atomic nucleus, the way nuclei interact among each other, and their impact in astrophysical processes. Detecting neutrons is difficult due to their lack of charge. CATRiNA is a novel neutron detector system which consists of 16 liquid scintillator detectors with deuterium (2H) as the interaction material. This paper describes the development and characterization of the CATRiNA detector array using neutron and gamma-ray sources, Monte-Carlo simulations, and neutrons with defined energy from the 7Li(p,n) nuclear reaction. CATRiNA is ready to be used in nuclear physics experimental research.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Study of the Al m 26 ( d , p ) Al 27 Reaction and the Influence of the Al 26 0 + Isomer on the Destruction of Al 26 in the Galaxy

The existence of 26 Al (t 1/2 = 7.17 Γ— 10 5 yr) in the interstellar medium provides a direct confirmation of ongoing nucleosynthesis in the Galaxy. The presence of a low-lying 0 + isomer ( 26 Al m ), however, severely complicates the astrophysical calculations. Here we present for the first time a study of the 26 Al m (d, p) 27 Al reaction using an isomeric 26 Al beam. The selectivity of this reaction allowed the study of β„“ = 0 transfers to T = 1/2, and T = 3/2 states in 27 Al . Mirror symmetry arguments were then used to constrain the 26 Al m (p,Ξ³) 27 Si reaction rate and provide an experimentally determined upper limit of the rate for the destruction of isomeric 26 Al via radiative proton capture reactions, which is expected to dominate the destruction path of 26 Al m in asymptotic giant branch stars, classical novae, and core collapse supernovae.

79 ASTRONOMY AND ASTROPHYSICS↗