A5014024640- Nuclear Physics and Applications
- Nuclear reactor physics and engineering
- Nuclear Materials and Properties
- Nuclear physics research studies
- Radiation Detection and Scintillator Technologies
- Atomic and Subatomic Physics Research
- Superconducting Materials and Applications
- Particle Detector Development and Performance
- Graphite, nuclear technology, radiation studies
- Magnetic confinement fusion research
- X-ray Spectroscopy and Fluorescence Analysis
- Radioactivity and Radon Measurements
- Nuclear Issues and Defense
- Advanced NMR Techniques and Applications
- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Radioactive element chemistry and processing
- Radiation Therapy and Dosimetry
- Quantum, superfluid, helium dynamics
- Radioactive contamination and transfer
- Science, Research, and Medicine
- Molten salt chemistry and electrochemical processes
- Space Science and Extraterrestrial Life
- Particle accelerators and beam dynamics
- Rare-earth and actinide compounds
Argonne National Laboratory
2020-2025
Lawrence Livermore National Laboratory
2014-2022
Los Alamos National Laboratory
2011-2020
National Nuclear Security Administration
2018
Embry–Riddle Aeronautical University
2018
Idaho National Laboratory
2011
George Washington University
2011
Örebro University
2000-2004
Joint Research Center
2002-2003
We measure the average spin of 144Ba, a common fragment produced in 252Cf(sf), as function total kinetic energy (TKE). combine twin Frisch-gridded ionization chamber with world-class 𝛾-ray spectrometer that was designed to high-multiplicity events, Gammasphere. The chamber, loaded 252Cf(sf) source, provides fission trigger, TKE fragments, approximate masses, and polar angle axis. Gammasphere yield, identification through tagging decay 𝛾 rays, feeding rotational bands fragments. determine...
The fragment mass and kinetic energy in neutron-induced fission of $^{238}\mathrm{U}$ has been measured for incident energies from 1 to 30 MeV at the Los Alamos Neutron Science Center. change distributions over this range were studied, transition highly asymmetric more symmetric is observed. A decrease average total $(\overline{\mathrm{TKE}})$ with increasing excitation observed, consistent previous experimental work. Additional structure multichance thresholds present...
The neutron induced fission cross sections of $^{240,242}\mathrm{Pu}$ have been measured as a function incident energy from 1 eV to 200 MeV. This is part an effort reduce experimental uncertainties nuclear data in support next generation reactors and transmutation technology. These two plutonium isotopes are nonfissile, the available limited below reaction threshold. present demonstrate presence 2.67 resonance $^{242}\mathrm{Pu}$ section, which missing ENDF/B-VII evaluation, resolve...
The 233, 234, 236, 238U fission cross sections have been measured relative to 235U(n, f) for incident neutron energies from 200 KeV MeV using time-of-flight at the Los Alamos Neutron Science Center. results are generally consistent with current ENDF/B-VII evaluation, but some discrepancies previous measurements above 20 30 observed. These part of a campaign measure high precision in support fast reactor technology.
The average total kinetic energy $(\overline{TKE})$ in $^{239}\mathrm{Pu}(n,f)$ has been measured for incident neutron energies between 0.5 and 50 MeV. experiment was performed at the Los Alamos Neutron Science Center (LANSCE) using time-of-flight technique, of fission fragments post-neutron emission a double Frisch-gridded ionization chamber. This represents first experimental study dependence $\overline{TKE}$ $^{239}\mathrm{Pu}$ above 6
This paper presents recent experimental results on the yield of prompt fission $\ensuremath{\gamma}$ rays from spontaneous $^{252}\mathrm{Cf}$. We use an ionization chamber to tag events and measure masses kinetic energies fragments trans-stilbene organic scintillators neutrons emitted by fragments. The combination allows us determine properties in coincidence with is known be influenced angular momenta (AM) present evidence indicating that total $\ensuremath{\gamma}$-ray multiplicity, i.e.,...
The 239Pu and 241Pu neutron-induced fission cross sections have been measured from subthermal energies to 200 MeV. These measurements are part of a campaign measure with high precision in support advanced fast reactor technology. Plutonium-241 is the most active target this program date, half-life 14.4 yr. results for good agreement previous experiments add new information limited knowledge on section above 30 Discrepancies up 30% between evaluations experimental data found region, which...
Properties of fission in $^{233}\mathrm{U}$ were measured at the Los Alamos Neutron Science Center incident neutron energies from thermal to 40 MeV. Fragments observed coincidence by using a twin ionization chamber with Frisch grids. The average total kinetic energy released and fragment mass yields determined double analysis method based on conservation momentum. experimental was validated $^{232}\mathrm{Th}$ absolute calibrated thermal-neutron--induced $^{235}\mathrm{U}$. This work...
Fission fragment angular distributions can provide an important constraint on fission theory, improving predictive codes, and are a prerequisite for precise ratio cross section measurement. Available anisotropy data is sparse, especially at neutron energies above 5 MeV. For the first time, three-dimensional tracking detector employed to study emission angles direct measurement of anisotropy. The Neutron Induced Fragment Tracking Experiment (NIFFTE) collaboration has deployed time projection...
An experimental program at Los Alamos Neutron Science Center (LANSCE) has been developed to precisely measure fission cross sections over ten decades in incident neutron energy for a range of actinides relevant advanced nuclear reactor designs and transmutation concepts. The first completed measurement is $^{237}\mathrm{Np}$($n,f$), the above-reaction-threshold part reported here. result close agreement with ENDF/B-VI region first- second-chance fission. section ratio $^{235}\mathrm{U}$...
The normalized $^{238}$U(n,f)/$^{235}$U(n,f) cross section ratio has been measured using the NIFFTE fission Time Projection Chamber from reaction threshold to $30$~MeV. fissionTPC is a two-volume MICROMEGAS time projection chamber that allows for full three-dimensional reconstruction of fission-fragment ionization profiles neutron-induced fission. measurement was performed at Los Alamos Neutron Science Center, where neutron energy determined time-of-flight. reported here first made with...
The total kinetic energy release in the neutron induced fission of $^{235}$U was measured (using white spectrum neutrons from LANSCE) for energies E$_{n}$ = 3.2 to 50 MeV. In this range average post-neutron drops 167.4 $\pm$ 0.7 162.1 0.8 MeV, exhibiting a local dip near second chance threshold. values and slope TKE vs. agree with previous measurements but do disagree (in magnitude) systematics. variances distributions are larger than expected apart structure threshold, invariant 11 We also...
We present a search for possible spin dependent interactions of the neutron with matter through exchange 1 bosons axial vector couplings as envisioned in extensions Standard Model. This was sought using slow polarimeter that passed transversely polarized neutrons by unpolarized slabs material arranged so this interaction would tilt plane polarization and develop component along momentum. The result rotation angle, $ϕ'_{V_5} = [2.8\pm\,4.6(stat.)\pm\,4.0(sys.)]\times 10^{-5}~\mbox{rad/m}$ is...
A template for estimating uncertainties (unc.) of measured neutron-induced fission, (n,f), cross-sections (cs) is presented. This preliminary not only lists all expected unc. sources but also supplies ranges unc., estimates correlations between the same and different experiments which can be used if information nonexistent. If this applied systematically when experimental covariances an evaluation, it may help in pinpointing missing individual datasets, identifying unreasonably low datasets....
The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has performed measurements with a fission time projection chamber (fissionTPC) to study the process by reconstructing full three-dimensional tracks of fragments and other ionizing radiation. amount linear momentum imparted fissioning nucleus incident neutron can be inferred measuring opening angle between fragments. Using this measured momentum, fragment angular distributions converted center-of-mass frame for...