Erratum: High spin states in {sup 151,153}Pr, {sup 157}Sm, and {sup 93}Kr[Phys. Rev. C 82, 034308 (2010)]
No abstract prepared.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
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Results for “INTERMEDIATE STATE”
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Band crossings in {sup 166}Ta
High-spin states in the odd-odd nucleus {sup 166}Ta are investigated through the 5n channel of the {sup 51}V+{sup 120}Sn reaction. Four new bands are observed and linked into the previous level scheme. Configurations for the bands are proposed, based on measured alignments and B(M1)/B(E2) transition strength ratios.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
{beta} decay of {sup 81}Zn and migrations of states observed near the N=50 closed shell
The {beta} decay of the N=51 nucleus {sup 81}Zn was studied by means of {beta}-{gamma} spectroscopy and from isotopically pure beams produced at the Holifield Radioactive Ion Beam Facility (HRIBF). We observe several competing {beta} transitions populating {sup 81}Ga that are interpreted as allowed Gamow-Teller decays to positive parity, core excited states, and first-forbidden decays to negative parity states. The measured {beta}-decay pattern suggests an assignment of I{sup {pi}}=5/2{sup +} for the {sup 81}Zn ground state. The systematics of core excited states in N=50 isotones indicate a strengthening of the N=40 subshell gap near {sup 78}Ni.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Low-energy structure of the even- A Ru 96 − 104 isotopes via g -factor measurements
Not Available
Taylor, M. J.↗
Observation of high-spin oblate band structures in {sup 141}Pm
The high-spin states of {sup 141}Pm have been investigated through the reaction {sup 126}Te({sup 19}F,4n) at a beam energy of 90 MeV. A previous level scheme has been updated with spins up to 49/2({h_bar}/2{pi}). Six collective bands at high spins are newly observed. Based on the systematic comparison, one band is proposed as a decoupled band; two bands with strong {Delta}I=1 M1 transitions inside the bands are suggested as the oblate bands with {gamma} {approx}-60 deg.; three other bands with large signature splitting have been proposed with the oblate-triaxial deformation with {gamma}{approx} -90 deg. The triaxial n-particle-n-hole particle rotor model calculations for one of the oblate bands in {sup 141}Pm are in good agreement with the experimental data. The other characteristics for these bands have been discussed.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Coulomb excitation of {sup 156}Gd
Multiple Coulomb-excitation experiments for {sup 156}Gd were made with a 118 MeV {sup 32}S beam and a 225 MeV {sup 58}Ni beam. The ground-state band, the {beta} band (K=0{sup +}), another K=0{sup +} band, and the {gamma} band (K=2{sup +}) were observed up to the 18{sup +}, 14{sup +}, 8{sup +}, and 12{sup +} states, respectively, while the octupole band (K=1{sup -}) was observed up to the 15{sup -} state, through the analysis of particle-{gamma}-{gamma} data. Compared with the results of the in-beam {gamma}-ray spectroscopy previously obtained, the present result suggests that a band crossing occurs in the {gamma} band. As for the {beta} band, the excitation energy of the 12{sup +} state was revised and the 14{sup +} state was newly observed in the present experiment. The intrinsic matrix elements entering the generalized intensity relations were obtained so as to reproduce the spin dependence of the E2 matrix elements extracted from the experimental results of particle-{gamma} angular correlation for the transitions within each band and between each band and the ground-state band by the least-squares search code gosia. The change of characters in the {beta} and {gamma} bands is discussed as a possible cause for the variation of the E2 matrix elements in the higher-spin region. The intrinsic matrix elements were also obtained for the E1 and E3 transitions from the ground-state band to the octupole band with K=1{sup -} through analysis by gosia.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Signature inversion in odd-odd {sup 114}Rh: First identification of high-spin states in very neutron-rich {sup 114}Rh and application of the triaxial projected shell model
High-spin excited states in the very neutron-rich nucleus {sup 114}Rh have been studied by examining the prompt {gamma} rays emitted in the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. A high-spin level scheme of {sup 114}Rh has been established for the first time with 13 new levels. The level scheme is proposed to be built on a 7{sup -} state. The existence of a relatively large signature splitting and an yrare band show features which may indicate triaxial deformation. The phenomenon of signature inversion has been observed in {sup 114}Rh at I=12 ({h_bar}/2{pi}). The observed signature inversion of {sup 114}Rh is interpreted successfully in terms of the triaxial projected shell model. Theoretical calculations suggest that the negative-parity, yrast band of {sup 114}Rh has the two-quasi-particle configuration of {pi}g{sub 9/2} x {nu}h{sub 11/2}, consistent with the systematics of odd-odd Rh isotopes. The signature inversion at spin 12 ({h_bar}/2{pi}) may be attributed to the change of rotational mode, from quasi-particle aligned rotation at low spins to collective rotation at high spins.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Shape coexistence in {sup 180}Hg studied through the {beta} decay of {sup 180}Tl
The {beta}{sup +}/EC decay of {sup 180}Tl and excited states in the daughter nucleus {sup 180}Hg have been investigated at the CERN On-Line Isotope Mass Separator (ISOLDE) facility. Many new low-lying energy levels were observed in {sup 180}Hg, of which the most significant are the 0{sub 2}{sup +} at 419.6 keV and the 2{sub 2}{sup +} at 601.3 keV. The former is the bandhead of an excited band in {sup 180}Hg assumed originally to be of prolate nature. From the {beta} feeding to the different states in {sup 180}Hg, the ground-state spin of {sup 180}Tl was deduced to be (4{sup -},5{sup -}).
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Amplitude Analysis and Measurement of the Time-dependent CP Asymmetry of B0 to KsKsKs Decays
We present the first results on the Dalitz-plot structure and improved measurements of the time-dependent CP-violation parameters of the process B{sup 0} {yields} K{sub S}{sup 0}K{sub S}{sup 0}K{sub S}{sup 0} obtained using 468 x 10{sup 6} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The Dalitz-plot structure is probed by a time-integrated amplitude analysis that does not distinguish between B{sup 0} and {bar B}{sup 0} decays. We measure the total inclusive branching fraction {Beta}(B{sup 0} {yields} K{sub S}{sup 0}K{sub S}{sup 0}K{sub S}{sup 0}) = (6.19 {+-} 0.48 {+-} 0.15 {+-} 0.12) x 10{sup -6}, where the first uncertainty is statistical, the second is systematic, and the third represents the Dalitz-plot signal model dependence. We also observe evidence for the intermediate resonant states f{sub 0}(980), f{sub 0}(1710), and f{sub 2}(2010). Their respective product branching fractions are measured to be (2.70{sub -1.19}{sup +1.25} {+-} 0.36 {+-} 1.17) x 10{sup -6}, (0.50{sub -0.24}{sup +0.46} {+-} 0.04 {+-} 0.10) x 10{sup -6}, and (0.54{sub -0.20}{sup +0.21} {+-} 0.03 {+-} 0.52) x 10{sup -6}. Additionally, we determine the mixing-induced CP-violation parameters to be S = -0.94{sub -0.21}{sup +0.24} {+-} 0.06 and C = -0.17 {+-} 0.18 {+-} 0.04, where the first uncertainty is statistical and the second is systematic. These values are in agreement with the standard model expectation.
43 PARTICLE ACCELERATORS↗
Spin Self-Rephasing and Very Long Coherence Times in a Trapped Atomic Ensemble
We perform Ramsey spectroscopy on the ground state of ultracold {sup 87}Rb atoms magnetically trapped on a chip in the Knudsen regime. Field inhomogeneities over the sample should limit the 1/e contrast decay time to about 3 s, while decay times of 58{+-}12 s are actually observed. We explain this surprising result by a spin self-rephasing mechanism induced by the identical spin rotation effect originating from particle indistinguishability. We propose a theory of this synchronization mechanism and obtain good agreement with the experimental observations. The effect is general and may appear in other physical systems.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Energy Density Functional Study of Nuclear Matrix Elements for Neutrinoless {beta}{beta} Decay
We present an extensive study of nuclear matrix elements (NME) for the neutrinoless double-beta decay of the nuclei {sup 48}Ca, {sup 76}Ge, {sup 82}Se, {sup 96}Zr, {sup 100}Mo, {sup 116}Cd, {sup 124}Sn, {sup 128}Te, {sup 130}Te, {sup 136}Xe, and {sup 150}Nd based on state-of-the-art energy density functional methods using the Gogny D1S functional. Beyond-mean-field effects are included within the generating coordinate method with particle number and angular momentum projection for both initial and final ground states. We obtain a rather constant value for the NMEs around 4.7 with the exception of {sup 48}Ca and {sup 150}Nd, where smaller values are found. We analyze the role of deformation and pairing in the evaluation of the NME and present detailed results for the decay of {sup 150}Nd.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Ionizing radiation effects in SONOS-based neuromorphic inference accelerators
Here, we evaluate the sensitivity of neuromorphic inference accelerators based on Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) charge trap memory arrays to total ionizing dose (TID) effects. Data retention statistics were collected for 16 Mbit of 40 nm SONOS digital memory exposed to ionizing radiation from a Co-60 source, showing good retention of the bits up to the maximum dose of 500 krad(Si). Using this data, we formulate a rate-equation-based model for the TID response of trapped charge carriers in the ONO stack, and predict the effect of TID on intermediate device states between ‘program’ and ‘erase’. This model is then used to simulate arrays of low-power, analog SONOS devices that store 8-bit neural network weights and support in situ matrix-vector multiplication. We evaluate the accuracy of the irradiated SONOS-based inference accelerator on two image recognition tasks – CIFAR-10 and the challenging ImageNet dataset – using state-of-the-art convolutional neural networks, such as ResNet-50. We find that across the datasets and neural networks evaluated, the accelerator tolerates a maximum TID between 10 krad(Si) and 100 krad(Si), with deeper networks being more susceptible to accuracy losses due to TID.
43 PARTICLE ACCELERATORS↗
Exceptional oxygen evolution reactivities on CaCoO 3 and SrCoO 3
We investigated the roles of covalent bonding, separation of surface oxygen, and electrolyte pH on the oxygen evolution reaction (OER) on transition metal oxides by comparing catalytic onset potentials and activities of CaCoO 3 and SrCoO 3 . Both cubic, metallic perovskites have similar Co IV intermediate spin states and onset potentials, but a substantially smaller lattice parameter and shorter surface oxygen separation make CaCoO 3 a more stable catalyst with increased OER activity. The onset potentials are similar, occurring where H + is removed from surface -OH - , but two competing surface reactions determine the catalytic activity. In one, the surface -O - is attacked by electrolyte OH - to form the surface -OOH - ; in the other, two -O - form a surface peroxide ion and an oxygen vacancy with electrolyte OH - attacking the oxygen vacancy. The second pathway can be faster if the surface oxygen separation is smaller.
36 MATERIALS SCIENCE↗
Thin film design of amorphous hafnium oxide nanocomposites enabling strong interfacial resistive switching uniformity
A design concept of phase-separated amorphous nanocomposite thin films is presented that realizes interfacial resistive switching (RS) in hafnium-oxide-based devices. The films are formed by incorporating an average of 7% Ba into hafnium oxide during pulsed laser deposition at temperatures ≤400°C. The added Ba prevents the films from crystallizing and leads to ~20-nm-thin films consisting of an amorphous HfO x host matrix interspersed with ~2-nm-wide, ~5-to-10-nm-pitch Ba-rich amorphous nanocolumns penetrating approximately two-thirds through the films. This restricts the RS to an interfacial Schottky-like energy barrier whose magnitude is tuned by ionic migration under an applied electric field. Resulting devices achieve stable cycle-to-cycle, device-to-device, and sample-to-sample reproducibility with a measured switching endurance of ≥10 4 cycles for a memory window ≥10 at switching voltages of ±2 V. Each device can be set to multiple intermediate resistance states, which enables synaptic spike-timing–dependent plasticity. The presented concept unlocks additional design variables for RS devices.
36 MATERIALS SCIENCE↗
Entanglement entropy fluctuations in quantum Ising chains
The behavior of Ising chains with the spin-spin interaction value {lambda} in a transverse magnetic field of constant intensity (h = 1) is considered. For a chain of infinite length, exact analytical formulas are obtained for the second central moment (dispersion) of the entropy operator S = -ln{rho} with reduced density matrix {rho}, which corresponds to a semi-infinite part of the model chain occurring in the ground state. In the vicinity of a critical point {lambda}{sub c} = 1, the entanglement entropy fluctuation {Delta}S (defined as the square root of dispersion) diverges as {Delta}S {approx} [ln(1/ vertical bar 1 - {lambda} vertical bar )]{sup 1/2}. For the known behavior of the entanglement entropy S, this divergence results in that the relative fluctuation {delta}S = {Delta}S/S vanishes at the critical point, that is, a state with almost nonfluctuating entanglement is attained.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Theory of two-step two-proton decays of nuclei
A general theory of many-body diagonal and nondiagonal one-proton decays of spherical and deformed nuclei is developed on the basis of an approach not employing R-matrix theory in describing deep-subbarrier alpha and one-proton decays of nuclei but relying on integral formulas for the widths with respect to these decays. With the aid of this theory and by means of a diagram technique, a formalism is developed for describing two-step two-proton decays of a (Z, A) parent nucleus, which proceed as two successive time-separated one-proton decays of the parent and intermediate [(Z − 1, A − 1)] nuclei, these decays being related by the Green’s function for the intermediate nucleus, G(Z − 1, A − 1). It is shown that, upon taking into account, in this Green’s function, intermediate-nucleus states that are on- and off-shell states for the decaying system, there arise, respectively, sequential and virtual two-proton decays of parent nuclei. Expressions for the widths with respect to sequential and virtual two-proton decays from the ground and excited states of spherical and deformed nuclei and for the angular and energy distributions of emitted protons are obtained.
74 ATOMIC AND MOLECULAR PHYSICS↗
Energy scan of cross sections for e{sup +}e{sup –} annihilation into quarkonia and light hadrons in the Belle experiment
The cross sections of the reactions e{sup +}e{sup –} → ϒ(nS)π{sup +}π{sup −} (n = 1, 2,3) and e{sup +}e{sup –} → h{sub b}(nP)π{sup +}π{sup −} (n = 1, 2) are measured as a function of the cms collision energy from their thresholds up to 11.02 GeV using the data of the Belle experiment operating at the KEKB e{sup +}e{sup –} collider. The peaks of the ϒ(10 860) and ϒ(11020) resonances are observed in the cross sections with an insignificant contribution of the continuum. The decay ϒ(11020) → h{sub b}(nP)π{sup +}π{sup −} is found to fully proceed through intermediate isovector states Z{sub b}(10610) and Z{sub b}(10650).
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗