A5002249535- Nuclear physics research studies
- Nuclear Physics and Applications
- Atomic and Molecular Physics
- Quantum Chromodynamics and Particle Interactions
- Astronomical and nuclear sciences
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Particle accelerators and beam dynamics
- Atomic and Subatomic Physics Research
- Nuclear reactor physics and engineering
- Radioactive Decay and Measurement Techniques
- Advanced Chemical Physics Studies
- Advanced NMR Techniques and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Mass Spectrometry Techniques and Applications
- Radiopharmaceutical Chemistry and Applications
- Radiation Detection and Scintillator Technologies
- Astro and Planetary Science
- Superconducting Materials and Applications
- Medical Imaging Techniques and Applications
- Rare-earth and actinide compounds
- Inorganic Fluorides and Related Compounds
- Electron and X-Ray Spectroscopy Techniques
- Quantum, superfluid, helium dynamics
- Radiation Therapy and Dosimetry
University of California, Berkeley
2016-2025
Oak Ridge Associated Universities
2008-2023
Oak Ridge Institute for Science and Education
1998-2023
Oak Ridge National Laboratory
2005-2022
Hearst (United States)
2022
Kurchatov Institute
2016
Louisiana State University
1995-2011
Rutgers, The State University of New Jersey
1999-2011
University of Tennessee at Knoxville
1995-2011
Colorado School of Mines
2011
By studying the 109Xe-->105Te-->101Sn superallowed alpha-decay chain, we observe low-lying states in 101Sn, one-neutron system outside doubly magic 100Sn. We find that spins of ground state (J = 7=2) and first excited 5=2) 101Sn are reversed with respect to traditional level ordering postulated for 103Sn heavier tin isotopes. Through simple arguments state-of-the-art shell model calculations explain this unexpected switch terms a transition from single-particle regime collective mode which...
Proton radioactivity from ${}^{141}\mathrm{Ho}$ and ${}^{131}\mathrm{Eu}$ has been identified. The proton transition an energy ${E}_{p}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1169(8)\mathrm{keV}$, a half-life ${t}_{1/2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}4.2(4)\mathrm{ms}$, is assigned to the decay of ${7/2}^{\ensuremath{-}}[523]$ Nilsson state. ${E}_{p}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}950(8)\mathrm{keV}$ 26(6) ms, consistent with either...
The new proton radioactivities ${}^{165,166,167}\mathrm{Ir}$ and ${}^{171}\mathrm{Au}$ have been observed. Ir isotopes were produced via the ${}^{92}\mathrm{Mo}{(}^{78}\mathrm{Kr}{,pxn)}^{165,166,167}\mathrm{Ir}$ reactions at 357 384 MeV. was ${}^{96}\mathrm{Ru}{(}^{78}\mathrm{Kr}{,p2n)}^{171}\mathrm{Au}$ reaction 389 emitters each identified by position, time, energy correlations between implantation of a residual nucleus into double-sided silicon strip detector, observation decay proton,...
Two new alpha emitters 109Xe and 105Te were identified through the observation of --> 101Sn alpha-decay chain. The nuclei produced in fusion-evaporation reaction 54Fe(58Ni,3n)109Xe studied using Recoil Mass Spectrometer at Holifield Radioactive Ion Beam Facility. transitions Ealpha = 4062 +/- 7 keV 3918 9 interpreted as l 2 0 from 7/2+ ground state (T1/2 13 ms) to 5/2+ a excited state, located 150 105Te. subsequent decay marks discovery lightest known alpha-decaying nucleus. measured...
We report total absorption spectroscopy measurements of ^{92}Rb, ^{96gs}Y, and ^{142}Cs β decays, which are the most important contributors to high energy ν[over ¯]_{e} spectral shape in nuclear reactors. These three decays contribute 43% flux near 5.5 MeV emitted by This is particularly interesting due features recently observed several experiments including Daya Bay, Double Chooz, RENO Collaborations. Measurements were conducted at Oak Ridge National Laboratory means proton-induced fission...
A complete set of electromagnetic moments, $B(E2;{0}_{1}^{+}\ensuremath{\rightarrow}{2}_{1}^{+}),\phantom{\rule{0.16em}{0ex}}Q({2}_{1}^{+})$, and $g({2}_{1}^{+})$, have been measured from Coulomb excitation semimagic $^{112,114,116,118,120,122,124}\text{Sn} (Z=50)$ on natural carbon titanium targets. The magnitude the $B(E2)$ values, to a precision $\ensuremath{\sim}4%$, disagree with recent lifetime study [Phys. Lett. B 695, 110 (2011)] that employed Doppler-shift attenuation method. values...
The structure of neutron-rich nuclei beyond $^{78}\mathrm{Ni}$ was studied using postaccelerated radioactive beams $^{83,84,85}\mathrm{Ga}$ utilizing $\ensuremath{\beta} \ensuremath{\gamma}$ and $\ensuremath{\beta}\ensuremath{-}n spectroscopy. Our data, when combined with energy level systematics, suggests a possible new spherical subshell closure at $N=58$ is created by the nearly degenerated $\ensuremath{\nu}3{s}_{1/2}$ $\ensuremath{\nu}2{d}_{5/2}$ orbitals being well separated from other...
High-precision measurements of $\ensuremath{\langle}{0}_{1}||M(E2)||{2}_{1}\ensuremath{\rangle}$ matrix elements from the Coulomb excitation ${}^{124,126,128}$Sn on a ${}^{12}$C target are presented. The extracted $B(E2)$ values decrease monotonically neutron midshell toward ${}^{132}$Sn double-shell closure, despite near constancy in first ${2}^{+}$ level energy. Furthermore, an enriched ${}^{50}$Ti target, combined with results provide measure static quadrupole moments, $Q({2}_{1}{}^{+})$...
Single-neutron states in $^{133}\mathrm{Sn}$ and $^{209}\mathrm{Pb}$, which are analogous to single-electron outside of closed atomic shells alkali metals, were populated by the ($^{9}\mathrm{Be}$, $^{8}\mathrm{Be}$) one-neutron transfer reaction inverse kinematics using particle-$\ensuremath{\gamma}$ coincidence spectroscopy. In addition, ${s}_{1/2}$ single-neutron hole-state candidate $^{131}\mathrm{Sn}$ was $^{10}\mathrm{Be}$). Doubly closed-shell $^{132}\mathrm{Sn}$ (radioactive)...
The β decays of neutron-rich nuclei near the doubly magic (78)Ni were studied at Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. half-lives (82)Zn (228±10 ms), (83)Zn (117±20 and (85)Ga (93±7 ms) determined for first time. These found to be very different from predictions global model used in astrophysical simulations. A new calculation was developed density functional model, which properly reproduced experimental values. robustness region allowed us...
An experiment was performed at Lawrence Berkeley National Laboratory's 88-in. Cyclotron to determine the mass number of a superheavy element. The measurement resulted in observation two α-decay chains, produced via Am243(Ca48,xn)291−xMc reaction, that were separated by mass-to-charge ratio (A/q) and identified combined BGS+FIONA apparatus. One event occurred A/q=284 assigned Nh284 (Z=113), daughter Mc288 (Z=115), while second A/q=288 Mc288. This represents first direct measurements numbers...
Improved neutron inelastic scattering cross sections have repeatedly been identified as a top priority nuclear data need, important for basic science and range of applications in energy, stockpile stewardship, proliferation detection. For the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mmultiscripts><a:mi mathvariant="normal">C</a:mi><a:mprescripts/><a:none/><a:mn>12</a:mn></a:mmultiscripts></a:math>(<c:math...
Ground and isomeric proton alpha decay branches are reported for the new isotope ${}^{177}\mathrm{Tl},$ produced by bombarding a ${}^{102}\mathrm{Pd}$ target with 370 MeV beam of ${}^{78}\mathrm{Kr}$ ions. The ground state is assigned as $\ensuremath{\pi}{s}_{1/2}$ configuration high spin isomer $(\ensuremath{\pi}{h}_{11/2}{)}^{\ensuremath{-}1}$ configuration. ground-state ${}^{171}\mathrm{Au}$ has been identified first time, ${}^{96}\mathrm{Ru}$ also Spectroscopic factors, masses,...
Production of the radioisotope 18F in novae is severely constrained by rate 18F(p,alpha)15O reaction. A resonance at E(c.m.)=330 keV may strongly enhance reaction rate, but its strength has been very uncertain. We have determined this important measuring cross section on and off using a radioactive beam ORNL Holifield Radioactive Ion Beam Facility. find that 1.48+/-0.46 eV, it dominates over significant range temperatures characteristic ONeMg novae.
The new proton radioactivity ${}^{185m}\mathrm{Bi}$ has been observed, produced via the ${}^{95}\mathrm{Mo}{(}^{92}\mathrm{Mo},pn{)}^{185}\mathrm{Bi}$ reaction. Its decay proceeds from low-lying ${\frac{1}{2}}^{+}$ intruder state in ${}^{185}\mathrm{Bi}$ to ${}^{184}\mathrm{Pb}$ ground with emission of a energy $1.585\ifmmode\pm\else\textpm\fi{}0.009\mathrm{MeV}$ and half-life $44\ifmmode\pm\else\textpm\fi{}16\ensuremath{\mu}\mathrm{s}$. This marks first observation above...
The B(E2;0(+)(1)-->2(+)(1)) values for the radioactive neutron-rich germanium isotopes (78,80)Ge and closed neutron shell nucleus 82Ge were measured at HRIBF using Coulomb excitation in inverse kinematics. These data allow a study of systematic trend between subshell closures N=40 50. B(E2) behavior approaching N=50 is similar to observed heavier isotopic chains. A comparison experimental results with model calculation demonstrates persistence gap strong sensitivity effective interaction.
The beta-delayed neutron branching ratios (P{betan}) for nuclei near doubly magic 78Ni have been directly measured using a new method combining high-resolution mass separation, reacceleration, and digital beta-gamma spectroscopy of 238U fission products. P{betan} values the very neutron-rich isotopes ;{76-78}Cu 83Ga were found to be much higher than previously reported predicted. Revised calculations betan process, accounting measurements an inversion pi2p{3/2} pi1f{5/2} orbitals, are in...
An alpha-decay branch of (1.4+/-0.4) x 10(-4) has been discovered in the decay 109I, which predominantly decays via proton emission. The measured Q(alpha) value 3918+/-21 keV allows indirect determination Q for emission from 105Sb 356+/-22 keV, is approximately 130 more bound than previously reported. This result relevant astrophysical rapid proton-capture process, would terminate 105Sn(p,gamma)106Sb(p,gamma)107Te(alpha decay)103Sn cycle at densities expected explosive hydrogen burning...
Fine structure in proton emission from the 7/2−[523] ground state and 1/2+[411] isomer deformed nucleus 141Ho was studied by means of fusion-evaporation reactions digital signal processing. Proton transitions to first excited 2+ 140Dy, with branching ratio Ipgs(2+)=0.9±0.2% Ipm(2+)=1.7±0.5%, were observed. The data are analyzed within non-adiabatic weak coupling model assuming a large quadrupole deformation daughter 140Dy as predicted self-consistent theory. Implications this result on...
Beta decay of 86Ga was studied by means β-neutron-γ spectroscopy. An isotopically pure ^{86}Ga beam produced at the Holifield Radioactive Ion Beam Facility using a resonance ionization laser ion source and high-resolution electromagnetic separation. The revealed half-life 43(-15)(+21) ms large β-delayed one-neutron two-neutron branching ratios P1n=60(10)% P2n=20(10)%. βγ populated 527 keV transition that is interpreted as deexcitation first 2+ state in N=54 isotone 86Ge suggests quick onset...
Two new proton emitting states in the deformed nuclei ${}^{140}\mathrm{Ho}$ ${(E}_{p}=1086\ifmmode\pm\else\textpm\fi{}10 \mathrm{keV},$ ${T}_{1/2}=6\ifmmode\pm\else\textpm\fi{}3 \mathrm{ms})$ and ${}^{141m}\mathrm{Ho}$ ${(E}_{p}=1230\ifmmode\pm\else\textpm\fi{}20 ${T}_{1/2}=8\ifmmode\pm\else\textpm\fi{}3 \ensuremath{\mu}\mathrm{s})$ have been identified. Experimental data are interpreted using coupled-channels Schr\"odinger equation with outgoing wave boundary conditions. The observed...
Fine structure in proton emission from the 3.1(3) mus activity of 145Tm was discovered by using a novel technique digital processing overlapping recoil implantation and decay signals. Proton transitions to ground state 144Er its first excited 2(+) at 0.33(1) MeV with branching ratio I(p)(2(+))=9.6+/-1.5% were observed. The wave function process analyzed particle-core vibration coupling models.