A5027609354- Nuclear physics research studies
- Nuclear Physics and Applications
- Nuclear reactor physics and engineering
- Astronomical and nuclear sciences
- Nuclear Materials and Properties
- High-Energy Particle Collisions Research
- Radiation Detection and Scintillator Technologies
- Quantum Chromodynamics and Particle Interactions
- Atomic and Molecular Physics
- Astro and Planetary Science
- Atomic and Subatomic Physics Research
- Particle Detector Development and Performance
- Advanced Thermodynamics and Statistical Mechanics
- Advanced Chemical Physics Studies
- Quantum, superfluid, helium dynamics
- CCD and CMOS Imaging Sensors
- High-pressure geophysics and materials
- X-ray Diffraction in Crystallography
- Magnetic confinement fusion research
- Radioactive element chemistry and processing
- Astronomical Observations and Instrumentation
- Twentieth Century Scientific Developments
- Particle accelerators and beam dynamics
- Image Processing Techniques and Applications
- Advanced NMR Techniques and Applications
Los Alamos National Laboratory
2013-2023
Texas A&M University
2003-2014
Charles University
2011
Stanford University
2011
Triangle Universities Nuclear Laboratory
2011
University of New York in Prague
2011
North Carolina State University
2011
Palo Alto University
2011
Lawrence Livermore National Laboratory
2009
Institute of Chemistry of the Slovak Academy of Sciences
2009
An extensive experimental survey of the features disassembly a small quasiprojectile system with $A~36$, produced in reactions 47 MeV/nucleon $^{40}\mathrm{Ar}\phantom{\rule{0.3em}{0ex}}+\phantom{\rule{0.3em}{0ex}}^{27}\mathrm{Al}$, $^{48}\mathrm{Ti}$, and $^{58}\mathrm{Ni}$, has been carried out. Nuclei excitation energy range 1--9 have investigated employing new method to reconstruct source. At an \ensuremath{\sim}5.6 many observables indicate presence maximal fluctuations deexcitation...
The reaction systems, $^{64}\mathrm{Zn}+^{58}\mathrm{Ni}$, $^{64}\mathrm{Zn}+^{92}\mathrm{Mo}$, $^{64}\mathrm{Zn}+^{197}\mathrm{Au}$, at 26, 35, and $47\phantom{\rule{0.2em}{0ex}}A\phantom{\rule{0.3em}{0ex}}\text{MeV}$, have been studied both in experiments with a $4\ensuremath{\pi}$ detector array, NIMROD, antisymmetrized molecular dynamics model calculations employing effective interactions corresponding to soft stiff equation of state (EOS). Direct experimental observables, such as...
The scaling of the yields heavy projectile residues from reactions 25 MeV/nucleon 86Kr projectiles with 124Sn,112Sn and 64Ni, 58Nitargets is studied. Isotopically resolved yield distributions fragments in range Z=10-36 these reaction pairs were measured MARS recoil separator angular 2.7-5.3 degrees. velocities residues, monotonically decreasing Z down to Z~26-28, are employed characterize excitation energy. ratios R21(N,Z) for each pair systems found exhibit isotopic (isoscaling), namely, an...
The isoscaling parameter $\alpha$, from the fragments produced in multifragmentation of $^{58}$Ni + $^{58}$Ni, $^{58}$Fe and reactions at 30, 40 47 MeV/nucleon, was compared with that predicted by antisymmetrized molecular dynamic (AMD) calculation based on two different nucleon-nucleon effective forces, namely Gogny Gogny-AS interaction. results show data agrees better choice interaction, resulting a symmetry energy $\sim$ 18-20 MeV. observed value indicate are formed reduced density 0.08 fm$^{-3}$.
The isoscaling properties of isotopically resolved projectile residues from peripheral collisions $^{86}\mathrm{Kr}$ (25 MeV/nucleon) $^{64}\mathrm{Ni}$ MeV/nucleon), and $^{136}\mathrm{Xe}$ (20 beams on various target pairs are employed to probe the symmetry energy coefficient nuclear binding energy. present study focuses heavy fragments produced in semiperipheral near onset multifragment emission (${E}^{*}/A=2$--3 MeV). For these fragments, measured average velocities used extract...
The evolution of the symmetry energy coefficient binding hot fragments with increasing excitation is explored in multifragmentation processes following heavy-ion collisions below Fermi energy. In this work, high-resolution mass spectrometric data on isotopic distributions projectile-like are systematically compared to calculations involving statistical model (SMM). Within SMM picture, present study suggests a gradual decrease primary from 25 MeV at compound nucleus regime towards 15 regime....
The symmetry energy and the isoscaling properties of fragments produced in multifragmentation $^{40}\mathrm{Ar}$, $^{40}\mathrm{Ca}+^{58}\mathrm{Fe}$, $^{58}\mathrm{Ni}$ reactions at 25, 33, 45, 53 MeV/nucleon were investigated within framework statistical model. parameters \ensuremath{\alpha}, from primary (hot) secondary (cold) fragment yield distributions, studied as a function excitation energy, isospin (neutron-to-proton asymmetry), energy. It is observed that parameter...
A large enhancement in the production of neutron-rich projectile residues is observed reactions a 25 MeV/nucleon 86Kr beam with 124Sn and 64Ni targets relative to predictions EPAX parametrization high-energy fragmentation, as well reaction less 112Sn target. hybrid model based on deep-inelastic transfer (DIT) code followed by statistical deexcitation accounts for part cross sections. The DIT simulation indicates that nuclides these associated peripheral nucleon exchange which neutron skins...
The cross sections and velocity distributions of projectile-like fragments from the reaction 25 MeV/nucleon 86Kr+64Ni have been measured using MARS recoil separator at Texas A&M, with special emphasis on neutron rich isotopes. Proton-removal pick-up isotopes observed large sections. A model deep-inelastic transfer (DIT) for primary interaction stage statistical evaporation code GEMINI deexcitation used to describe properties product distributions. results also compared EPAX parametrization...
Radiative neutron capture reaction was measured in the resolved resonance region for ${}^{152,154,156,158}$Gd targets with Detector Advanced Neutron Capture Experiments $\ensuremath{\gamma}$-ray calorimeter at Los Alamos Science Center. The energy spectra different multiplicities were obtained several $s$-wave resonances each nucleus. These analyzed within extreme statistical model to provide unique information on photon strength functions and especially scissors mode odd Gd isotopes. main...
The isotopic properties of the primary and secondary fragment yield distribution in multifragmentation $^{58}\mathrm{Fe}+^{58}\mathrm{Ni}$ $^{58}\mathrm{Fe}+^{58}\mathrm{Fe}$ reactions are studied with respect to $^{58}\mathrm{Ni}+^{58}\mathrm{Ni}$ reaction at 30, 40, 47 MeV/nucleon. reduced neutron proton densities from observed show undergo strongly deexcitations. effect is small lowest excitation energy smallest neutron-to-proton ratio becomes large higher energies ratio. symmetry...
The kinetic-energy variation of emitted light clusters has been employed as a clock to explore the time evolution temperature for thermalizing composite systems produced in reactions 26A, 35A, and 47A MeV Zn64 with Ni58, Mo92, Au197. For each system investigated, double-isotope ratio curve exhibits high maximum apparent temperature, range 10–25 MeV, at ejectile velocity. These values increase increasing projectile energy decrease target mass. which is reached ranges from 80 130 fm/c after...
The ${}^{155}$Gd($n,\ensuremath{\gamma}$) reaction was measured with the DANCE $\ensuremath{\gamma}$-ray calorimeter (consisting of 160 BaF${}_{2}$ scintillation detectors) at Los Alamos Neutron Science Center. energy spectra for different multiplicities were obtained $s$-wave resonances. shapes these compared simulations based on use dicebox statistical model code. Simulations showed that photon strength functions (PSFs) successfully describing decay ${}^{156}$Gd are very similar to PSFs...
A wide variety of observables indicate that maximal fluctuations in the disassembly hot nuclei with $A\ensuremath{\sim}36$ occur at an excitation energy $5.6\ifmmode\pm\else\textpm\fi{}0.5\phantom{\rule{0.3em}{0ex}}\text{MeV}∕\text{nucleon}$ and temperature $8.3\ifmmode\pm\else\textpm\fi{}0.5\phantom{\rule{0.3em}{0ex}}\text{MeV}$. Associated this point are a number quantitative indicators apparent critical behavior. The associated caloric curve does not appear to show flattening such as seen...
Simultaneous measurement of both neutrons and charged particles emitted in the reaction $^{64}\mathrm{Zn}$ + at 45 MeV/nucleon allows comparison neutron to proton ratio midrapidity with that projectile rapidity. The evolution $N/Z$ rapidity regimes increasing centrality is examined. For completely reconstructed material one finds above overall system. In contrast, for quasiprojectile below This difference provides most complete evidence date enrichment nuclear matter expense quasiprojectile.
Peripheral collisions of $^{40}\mathrm{Ca}$ and $^{48}\mathrm{Ca}$ projectiles at 32 MeV/nucleon on $^{112}\mathrm{Sn}$ $^{124}\mathrm{Sn}$ targets were studied in this work. The fragments the projectile-like source (quasiprojectile) collected with a charged-particle multidetector array. average value neutron-to-proton ratio $N/Z$ quasiprojectiles formed reactions was determined two approaches. first is direct reconstruction approach using isotopically resolved hindered by undetected...
Understanding mix in inertial confinement fusion (ICF) experiments at the National Ignition Facility requires diagnosis of charged-particle reactions within an imploded target. Radiochemical diagnostics these are currently under study by scientists Los Alamos and Lawrence Livermore Laboratories. Measurement assay activated debris tracer gases from Presented below is overview prompt radiochemistry diagnostic development efforts, including a discussion interest as well progress being made to...
The ${}^{155}$Gd($n$,$\ensuremath{\gamma}$) reaction was measured with the DANCE $\ensuremath{\gamma}$-ray calorimeter at Los Alamos Neutron Science Center. Spins were determined for $s$-wave resonances by analysis of multiplicity distributions. performed a pattern recognition method. resulting level densities $J=1$ and 2 are in qualitative agreement expected 2$J$ $+$ 1 dependence. average resonance spacing to be ${D}_{0}=1.62$ $\ifmmode\pm\else\textpm\fi{}$ 0.15 eV. Analysis neutron code...
The cross section of the neutron capture reaction $^{176}\mathrm{Lu}(n,\ensuremath{\gamma})$ has been measured for a wide incident energy range with Detector Advanced Neutron Capture Experiments at Los Alamos Science Center. thermal was determined to be $(1912\ifmmode\pm\else\textpm\fi{}132)$ b one Lu natural isotopes, $^{176}\mathrm{Lu}$. resonance part and compared Mughabghab's atlas using $R$-matrix code, sammy. At higher energies sections are ENDF/B-VII.1, JEFF-3.2, BRC evaluated nuclear...
Isotopic composition of the fragments emitted during multifragmentation ${}^{58}\mathrm{Ni}{+}^{58}\mathrm{Ni},$ ${}^{58}\mathrm{Fe}{+}^{58}\mathrm{Ni},$ ${}^{58}\mathrm{Ni}{+}^{58}\mathrm{Fe},$ and ${}^{58}\mathrm{Fe}{+}^{58}\mathrm{Fe}$ was studied at beam energies 30, 40, 47 MeV/nucleon. Within context a grand-canonical approach, relative free neutron proton densities, extracted from measured isotope isotone yield ratios, suggest that content vapor phase increases with isospin $(N/Z)$...
By combining data from a charged particle Ni58+Ni58 experiment at 52 MeV/nucleon with an Ar36+Ni58 50 for which free neutrons have been detected, increase in the neutron to proton ratio of whole nuclear material midrapidity has experimentally observed reaction MeV/nucleon. The neutron-to-proton quasi-projectile emission is analyzed same reactions and seen decrease below initial system. Those observations suggest that asymmetric exchange protons between quasiprojectile region exists.7...