Mass measurements of neutron-deficient Y, Zr, and Nb isotopes and their impact on rp and νp nucleosynthesis processes

© 2018 The Authors. Published by Elsevier B.V. This manuscript is made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licence (CC BY-NC-ND 4.0). For further details please see: https://creativecommons.org/licenses/by-nc-nd/4.0/Using isochronous mass spectrometry at the experimental storage ring CSRe in Lanzhou, the masses of 82Zr and 84Nb were measured for the first time with an uncertainty of ∼10 keV, and the masses of 79Y, 81Zr, and 83Nb were re-determined with a higher precision. The latter are significantly less bound than their literature values. Our new and accurate masses remove the irregularities of the mass surface in this region of the nuclear chart. Our results do not support the predicted island of pronounced low α separation energies for neutron-deficient Mo and Tc isotopes, making the formation of Zr–Nb cycle in the rp-process unlikely. The new proton separation energy of 83Nb was determined to be 490(400) keV smaller than that in the Atomic Mass Evaluation 2012. This partly removes the overproduction of the p-nucleus 84Sr relative to the neutron-deficient molybdenum isotopes in the previous νp-process simulations.Peer reviewe

A study of charged kappa in J/ψ→K±Ksπ∓π0J/\psi \to K^{\pm} K_s \pi^{\mp} \pi^0

Based on $58 \times 10^6$ $J/\psi$ events collected by BESII, the decay $J/\psi \to K^{\pm} K_s \pi^{\mp} \pi^0$ is studied. In the invariant mass spectrum recoiling against the charged $K^*(892)^{\pm}$, the charged $\kappa$ particle is found as a low mass enhancement. If a Breit-Wigner function of constant width is used to parameterize the kappa, its pole locates at $(849 \pm 77 ^{+18}_{-14}) -i (256 \pm 40 ^{+46}_{-22})$ MeV/$c^2$. Also in this channel, the decay $J/\psi \to K^*(892)^+ K^*(892)^-$ is observed for the first time. Its branching ratio is $(1.00 \pm 0.19 ^{+0.11}_{-0.32}) \times 10^{-3}$.Comment: 14 pages, 4 figure

Direct Measurements of Absolute Branching Fractions for D0 and D+ Inclusive Semimuonic Decays

By analyzing about 33 $\rm pb^{-1}$ data sample collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we directly measure the branching fractions for the neutral and charged $D$ inclusive semimuonic decays to be $BF(D^0 \to \mu^+ X) =(6.8\pm 1.5\pm 0.7)$ and $BF(D^+ \to \mu^+ X) =(17.6 \pm 2.7 \pm 1.8)$, and determine the ratio of the two branching fractions to be $\frac{BF(D^+ \to \mu^+ X)}{BF(D^0 \to \mu^+ X)}=2.59\pm 0.70 \pm 0.25$

Measurements of the observed cross sections for exclusive light hadron production in e^+e^- annihilation at \sqrt{s}= 3.773 and 3.650 GeV

By analyzing the data sets of 17.3 pb$^{-1}$ taken at $\sqrt{s}=3.773$ GeV and 6.5 pb$^{-1}$ taken at $\sqrt{s}=3.650$ GeV with the BESII detector at the BEPC collider, we have measured the observed cross sections for 12 exclusive light hadron final states produced in $e^+e^-$ annihilation at the two energy points. We have also set the upper limits on the observed cross sections and the branching fractions for $\psi(3770)$ decay to these final states at 90% C.L.Comment: 8 pages, 5 figur

Measurements of the observed cross sections for e+e−→e^+e^-\to exclusive light hadrons containing π0π0\pi^0\pi^0 at s=3.773\sqrt s= 3.773, 3.650 and 3.6648 GeV

By analyzing the data sets of 17.3, 6.5 and 1.0 pb$^{-1}$ taken, respectively, at $\sqrt s= 3.773$, 3.650 and 3.6648 GeV with the BES-II detector at the BEPC collider, we measure the observed cross sections for $e^+e^-\to \pi^+\pi^-\pi^0\pi^0$, $K^+K^-\pi^0\pi^0$, $2(\pi^+\pi^-\pi^0)$, $K^+K^-\pi^+\pi^-\pi^0\pi^0$ and $3(\pi^+\pi^-)\pi^0\pi^0$ at the three energy points. Based on these cross sections we set the upper limits on the observed cross sections and the branching fractions for $\psi(3770)$ decay into these final states at 90% C.L..Comment: 7 pages, 2 figure

Enhanced surface mechanical properties of structural steels by a surface nano-crystallization based duplex treatment processing

Structural steels are widely used in engineering fields. Generally, they have the advantage of lower prices due to less precious alloy elements contained; however, their properties, especially the surface properties are inferior to high alloy steels. Surface engineering are of importance in improving surface properties of steels, and even a 'new' surface layer with high performances can be produced by surface technologies on low cost structural steels with ordinary properties. The researches of last decade have shown that surface nanocrystallization (SNC) can markedly improve surface mechanical properties of metallic materials and accelerate thermal diffusion of N, Cr, etc atoms. In this work we try to combine SNC with hard coating technology into a new duplex treatment processing to enhance surface mechanical properties of structural steels. AISI 304 stainless steel was firstly studied. The steel was subjected to surface mechanical attrition treatment to form a nanocrystalline surface layer, and diamond-like carbon (DLC) film was deposited on SNCed and coarse grained 304 steel substrates by a closed-field unbalanced magnetron sputtering ion-plating system. The results by microhardness test, adhesion tests of indentation and scratch methods, wear and cyclic impact tests show that the hardness and load-bearing capability of the film/substrate system are obviously increased by SNC; film adhesion, wear resistance and cyclic impact resistance are also improved by SNC. The enhanced surface mechanical properties of 304 stainless steel by the hybrid treatment processing are related to the hard composite surface layer with good integrity. The advantages of this hybrid treatment over the single treatments or the traditional hybrid treatment consisting of nitriding and hard coating are discussed. The work on other structural steels e.g. low or medium carbon steels is now under way. The SNC based hybrid treatment will find potential applications in machine parts or other engineering fields

Anomalous Line-Shape of Cross Sections for e+e−→Hadronse^+e^- \to {\rm Hadrons} in the Center-of-Mass Energy Region between 3.650 and 3.872 GeV

We observe an obvious anomalous line-shape of the $e^+e^- \to {\rm hadrons}$ total cross sections in the energy region between 3.700 and 3.872 GeV from the data samples taken with the BES-II detector at the BEPC Collider. Re-analysis of the data shows that it is inconsistent with the explanation for only one simple $\psi(3770)$ resonance with a statistical significance of $7\sigma$. The anomalous line-shape may be explained by two possible enhancements of the inclusive hadron production near the center-of-mass energies of 3.764 GeV and 3.779 GeV, indicating that either there is likely a new structure in addition to the $\psi(3770)$ resonance around 3.773 GeV, or there are some physics effects reflecting the $D\bar D$ production dynamics

Measurements of the observed cross sections for e+e -> exclusive light hadrons containing K^S_0 meson at \sqrt{s} = 3.773 and 3.650 GeV

By analyzing the data sets of 17.3 pb$^{-1}$ taken at $\sqrt s= 3.773$ GeV and of 6.5 pb$^{-1}$ taken at $\sqrt s= 3.650$ GeV with the BES-II detector at the BEPC collider, we measure the observed cross sections for the exclusive light hadron final states of $K_S^0K^-\pi^+$, $K_S^0K^-\pi^+\pi^0$, $K_S^0K^-\pi^+\pi^+\pi^-$, $K_S^0K^-\pi^+\pi^+\pi^-\pi^0$, $K_S^0K^-\pi^+\pi^+\pi^+\pi^-\pi^-$ and $K_S^0K^-\pi^+\pi^0\pi^0$ produced in $e^+ e^-$ annihilation at the two energy points. We set the upper limits on the observed cross sections and the branching fractions for $\psi(3770)$ decay to these final states at 90% C.L..Comment: 6 pages, 1 figur

Direct measurement of the absolute branching fraction for D+→Kˉ0μ+νμD^+ \to {\bar K}^0\mu^+\nu_\mu and determination of Γ(D0→K−μ+νμ)/Γ(D+→Kˉ0μ+νμ) \Gamma (D^0 \to K^-\mu^+\nu_\mu)/\Gamma (D^+ \to {\bar K}^0\mu^+\nu_\mu)

The absolute branching fraction for the decay $D^+ \to {\bar K}^0\mu^+\nu_\mu$ is determined using $5321 \pm 149 \pm160$ singly tagged $D^-$ sample from the data collected around 3.773 GeV with the BESII detector at the BEPC collider. In the system recoiling against the singly tagged $D^-$ mesons, $28.7 \pm 6.4$ events for $D^+ \to {\bar K}^0\mu^+\nu_\mu$ are observed. These yield the absolute branching fraction to be $BF(D^+ \to {\bar K}^0\mu^+\nu_\mu) = (10.3\pm2.3\pm0.8)$. The ratio of the two partial widths for the decays $D^0 \to K^-\mu^+\nu_\mu$ and $D^+ \to {\bar K}^0\mu^+\nu_\mu$ is determined to be $\Gamma (D^0 \to K^-\mu^+\nu_\mu)/\Gamma (D^+ \to {\bar K}^0\mu^+\nu_\mu) = 0.87 \pm 0.24 \pm 0.15$.Comment: 6 pages, 5 figure