S. J. Zhu

Bio: S. J. Zhu is an academic researcher from Tsinghua University. The author has contributed to research in topics: Neutron & Spontaneous fission. The author has an hindex of 14, co-authored 105 publications receiving 845 citations.

Theoretical simulation for identical bands

Abstract: The frequency of occurrence of identical bands in superdeformed and normal-deformed nuclei is studied by carrying out a statistical analysis of a large number of rotational bands, which are generated with the reflection asymmetric shell model. The frequency of occurrence and the behaviors of identical bands revealed in the statistical analysis of the experimental bands were generally reproduced by the present theoretical simulation. This would indicate that the nuclear mean-field approximation plus the beyond mean-field one, like angular-momentum and parity projections, can explain the phenomena of identical bands even though there is no available theory that can reach the accuracy of identity between the specific identical bands. Furthermore, the octupole effect on the identical bands is discussed. The present theoretical simulation shows that more correlations may lead to more identical bands.

Zero neutron emission in spontaneous fission of 252Cf: a form of cluster radioactivity

Abstract: By using the triple gamma coincidence technique with 20 Ge detectors at the Holifield Laboratory in the spontaneous fission of 252Cf, neutronless fragmentations, like 104Mo-148Ba, 106Mo-146Ba, 108Mo-144Ba and 104Zr-148Ce, are experimentally observed directly for the first time. When zero neutron emission spontaneous fission occurs, essentially all the available energy goes into the total kinetic energy of the fragments (cold fission). This process is seen theoretically to be an extension of cluster radioactivity, which involves the emission of one light fragment like 14C, 20O, (24)Ne or 28Mg to nearly equal fragments. In the neutronless spontaneous fission reported here, double fine structures (i.e. decays to the excited states of both fragments) are observed experimentally in contrast to fine structure in only the heavy partner populated by the light partner in earlier cluster radioactivity work. Neutronless spontaneous fission is discussed in the framework of cluster radioactivity.

Cold (neutronless) {alpha} ternary fission of {sup 252}Cf

Abstract: The phenomenon of cold (neutronless) alpha ternary fission in spontaneous fission of {sup 252}Cf was experimentally observed by triple gamma coincidence technique with Gammasphere with 72 gamma-ray detectors. Correlated pairs of {sub 36}Kr-{sub 60}Nd, {sub 38}Sr-{sub 58}Ce, {sub 40}Zr-{sub 56}Ba, {sub 42}Mo-{sub 54}Xe, {sub 44}Ru-{sub 52}Te, and {sub 46}Pd-{sub 50}Sn were observed to be associated with {alpha} ternary fission of {sup 252}Cf. Yields of cold {alpha} ternary fission were extracted. {copyright} {ital 1998} {ital The American Physical Society}

Octupole correlations in neutron-rich {sup 145,147}La nuclei: Coriolis-limit-coupling bands with aligned h{sub 11/2} proton

Abstract: Several new high-spin states are observed in the prompt $\ensuremath{\gamma}$-rays emitted from the neutron-rich, odd-$Z$ ${}^{145,147}\mathrm{La}$ fragments produced in the spontaneous fission of ${}^{252}\mathrm{Cf}$ Alternating parity bands are extended up to spins 41/2 and 43/2 in ${}^{145,147}\mathrm{La},$ respectively A new band completes the evidence for two sets of parity doublets expected for octupole correlations Eight $B(E1)/B(E2)$ ratios (four new) between two bands in ${}^{145}\mathrm{La}$ are all essentially constant and somewhat larger than similar ratios in ${}^{143,144}\mathrm{Ba},$ where stable octupole deformation and/or correlations are reported The new ratios out of the ${31/2}^{\ensuremath{-}}$ levels in both nuclei show a sharp spike compared to other states, presumably from a strong reduction in $E2$ strengths in this backbending region In ${}^{145}\mathrm{La},$ collective bands show competition and coexistence between symmetric and asymmetric shapes Band crossings occur in both nuclei around $\ensuremath{\Elzxh}\ensuremath{\omega}\ensuremath{\approx}026--030 \mathrm{MeV}$ Their backbends are associated with the alignment of two ${i}_{13/2}$ neutrons according to cranked shell model calculations

Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China

Abstract: Fine-particle pollution associated with winter haze threatens the health of more than 400 million people in the North China Plain. Sulfate is a major component of fine haze particles. Record sulfate concentrations of up to ~300 μg m −3 were observed during the January 2013 winter haze event in Beijing. State-of-the-art air quality models that rely on sulfate production mechanisms requiring photochemical oxidants cannot predict these high levels because of the weak photochemistry activity during haze events. We find that the missing source of sulfate and particulate matter can be explained by reactive nitrogen chemistry in aerosol water. The aerosol water serves as a reactor, where the alkaline aerosol components trap SO 2 , which is oxidized by NO 2 to form sulfate, whereby high reaction rates are sustained by the high neutralizing capacity of the atmosphere in northern China. This mechanism is self-amplifying because higher aerosol mass concentration corresponds to higher aerosol water content, leading to faster sulfate production and more severe haze pollution.

The statistical mechanics of the electrical double layer

Abstract: Mise au point. Rappel des equations fondamentales et des conditions d'etude. Donnees sur le modele de l'ion ponctuel et la theorie de Gouy-Chapman, sur les theories de la double couche pour les electrolytes modeles primitifs, sur la comparaison de la theorie avec des simulations dans le cas des electrolytes symetriques et enfin sur la mise au point d'un modele basique