U. Greife
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View article: Status update on the NIFFTE high precision fission cross section measurement program
Status update on the NIFFTE high precision fission cross section measurement program Open
The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) program has been underway for nearly two years. The program's mission is to measure fission cross sections of the primary fissionable and fissile materials ({sup 235}U, {sup…
View article: Measurement of Charge State Distributions using a Scintillation Screen
Measurement of Charge State Distributions using a Scintillation Screen Open
Absolute cross sections measured using electromagnetic devices to separate and detect heavy recoiling ions need to be corrected for charge state fractions. Accurate prediction of charge state distributions using theoretical models is not a…
View article: Understanding globular cluster abundances through nuclear reactions
Understanding globular cluster abundances through nuclear reactions Open
Globular clusters contain multiple stellar populations, with some previous generation of stars polluting the current stars with heavier elements. Understanding the history of globular clusters is helpful in understanding how galaxies merge…
View article: First (p,n) reaction measurement in inverse kinematics with SECAR
First (p,n) reaction measurement in inverse kinematics with SECAR Open
Nucleosynthesis in the ν p-process occurs in regions of slightly proton-rich nuclei in the neutrino-driven wind of core-collapse supernovae. The process proceeds via a sequence of (p, γ ) and (n,p) reactions, and depending on the condition…
View article: A technique for studying (n,p) reactions of astrophysical interest using radioactive beams with SECAR
A technique for studying (n,p) reactions of astrophysical interest using radioactive beams with SECAR Open
The formation of nuclei in slightly proton-rich regions of the neutrino-driven wind of core-collapse supernovae could be attributed to the neutrino-p process (νp-process). As it proceeds via a sequence of (p,γ) and (n,p) reactions, it may …
View article: Elastic scattering of 3He+4He with SONIK
Elastic scattering of 3He+4He with SONIK Open
Measurements of the elastic scattering cross section of 3He and 4He are important in order to improve constraints on theoretical models of 4He(3He,g)7Be, a key reaction in Big Bang nucleosynthesis and solar neutrino production. The astroph…
View article: The DIANA underground accelerator facility project at DUSEL laboratory
The DIANA underground accelerator facility project at DUSEL laboratory Open
The DIANA project (Dakota Ion Accelerators for Nuclear Astrophysics) is a collaboration between the University of Notre Dame, Colorado School of Mines, Regis University, University of North Carolina, Western Michigan University, and Lawren…
View article: Astrophysically important 26Si states studied with the 28Si(p,t)26Si reaction
Astrophysically important 26Si states studied with the 28Si(p,t)26Si reaction Open
The production of the 26Al radioisotope in astrophysical environments is not understood, in part, because of large uncertainties in key nuclear reaction rates. The 25Al(p, γ)26Si reaction is one of the most important, but its rate is very …
View article: SECAR: A recoil separator for nuclear astrophysics
SECAR: A recoil separator for nuclear astrophysics Open
Proton-and alpha-capture reactions on unstable proton-rich nuclei power astrophysical explosions like novae and X-ray bursts. Direct measurements of these reactions are crucial for understanding the mechanisms behind these explosions and t…
View article: Properties of correlated fission fragments from neutron induced fission of Np-237 at incident neutron energies between 200 keV and 100 MeV
Properties of correlated fission fragments from neutron induced fission of Np-237 at incident neutron energies between 200 keV and 100 MeV Open
Neutron-induced fission of $^{237}$Np has been measured over a wide range of incident neutron energies using a twin Frisch-gridded ionization chamber (TFGIC) and a thin-backed $^{237}$Np target. These measurements were performed at the Los…
View article: Measurement of material isotopics and atom number ratio with alpha-particle spectroscopy for the NIFFTE fission Time Projection Chamber actinide target
Measurement of material isotopics and atom number ratio with alpha-particle spectroscopy for the NIFFTE fission Time Projection Chamber actinide target Open
We present the results of a measurement of isotopic concentrations and atomic number ratio of a double-sided actinide target with alpha-spectroscopy and mass spectrometry. The double-sided actinide target, with primarily Pu-239 on one side…
View article: Study of the <sup>7</sup>Be(α,γ)<sup>11</sup>C reaction with DRAGON for vp–process nucleosynthesis
Study of the <sup>7</sup>Be(α,γ)<sup>11</sup>C reaction with DRAGON for vp–process nucleosynthesis Open
The production of the p–nuclei is one of the unsolved puzzles in nuclear astrophysics. A possible mechanism is the nucleosynthesis in the neutrino–driven winds of core–collapse supernovae (νp–process), but it carries uncertainties, mostly …
View article: Neutron-induced fission fragment angular distributions, anisotropy, and linear momentum transfer measured with the NIFFTE fission time projection chamber
Neutron-induced fission fragment angular distributions, anisotropy, and linear momentum transfer measured with the NIFFTE fission time projection chamber Open
The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has performed measurements with a fission time projection chamber (fissionTPC) to study the fission process by reconstructing full three-dimensional tracks of …
View article: Particle decay of astrophysically-important <sup>19</sup>Ne levels
Particle decay of astrophysically-important <sup>19</sup>Ne levels Open
The 15 O(α,γ) 19 Ne reaction is an important trigger reaction leading to the rapid proton ( rp ) capture process in X-ray bursts. The primary uncertainty in determining its astrophysical rate is the uncertain α branching ratios of levels n…
View article: 1H(n,el) as a Cross Section Reference in a White Source Neutron Beam With the fissionTPC
1H(n,el) as a Cross Section Reference in a White Source Neutron Beam With the fissionTPC Open
We provide a quantitative description of a method to measure neutron-induced fission cross sections in ratio to elastic hydrogen scattering in a white-source neutron beam with the fission Time Projection Chamber. This detector has measured…
View article: Proton Capture on 34S in the Astrophysical Energy Regime
Proton Capture on 34S in the Astrophysical Energy Regime Open
Novae are unique environments for nucleosynthesis, fueled by the thermonuclear runaway of material accreted onto the surface of the white dwarf component of a close binary system. In order to properly model these systems, precise knowledge…
View article: $s$-wave scattering lengths for $^7$Be+p system from $R$-matrix analysis
$s$-wave scattering lengths for $^7$Be+p system from $R$-matrix analysis Open
The astrophysical S factor for the radiative proton capture reaction on Be7 (S17) at low energies is affected by the s-wave scattering lengths. We report the measurement of elastic and inelastic scattering cross sections for the Be7+p syst…
View article: Total kinetic energy and fragment mass distributions from fission of Th-232 and U-233
Total kinetic energy and fragment mass distributions from fission of Th-232 and U-233 Open
Properties of fission in Th-232 and U-233 were studied at the Los Alamos Neutron Science Center at incident neutron energies from subthermal to 40 MeV. Fission fragments are observed in coincidence using a twin ionization chamber with Fris…