Assault frequency and preformation probability of the alpha emission process

A study of the assault frequency and preformation factor of the α-decay description is performed from the experimental α-decay constant and the penetration probabilities calculated from the generalized liquid-drop model (GLDM) potential barriers. To determine the assault frequency a quantum-mechanical method using a harmonic oscillator is introduced and leads to values of around 1021 s−1, similar to the ones calculated within the classical method. The preformation probability is around 10−1-10−2. The results for even-even Po isotopes are discussed for illustration. While the assault frequency presents only a shallow minimum in the vicinity of the magic neutron number 126, the preformation factor and mainly the penetrability probability diminish strongly around N=126

Systematical calculation of alpha decay half-lives with a generalized liquid drop model

International audienceA systematic calculation of α decay half-lives is presented for even-even nuclei between Te and Z=118 isotopes. The potential energy governing α decay has been determined within a liquid drop model including proximity effects between the α particle and the daughter nucleus and taking into account the experimental Q value. The α decay half-lives have been deduced from the WKB barrier penetration probability. The α decay half-lives obtained agree reasonably well with the experimental data

Treatment of DomesticWastewaterwith Simultaneous Electricity Generation in Microbial Fuel Cell under Continuous Operation

In order to apply microbial fuel cell (MFC) process more practically in wastewater treatment, both power generation and removal of chemical oxygen demand (COD) were examined in an air-cathode MFC fed with domestic wastewater under continuous operation. At a hydraulic retention time (HRT) of 2.0 h, the air-cathode MFC was able to generate electricity from domestic wastewater with a maximum power density of P = 103 2 mWm–2 (5772 mW m–3) and an average Coulomb efficiency (CE) of 18.4%; meanwhile, to achieve an average COD removal up to 71 %. Increasing HRT from 2h to 10–30 h was found to be more effective for COD removal, however, instability in voltage output was also observed. An increased power generation of 1734mW m–2 (9648 mW m–3) was obtained with the aid of NaCl addition at a mass fraction of w = 2.4 %, because of an elevated conductivity of the solution with accord internal resistance of 227 0

Non-Markovian entanglement dynamics in coupled superconducting qubit systems

We theoretically analyze the entanglement generation and dynamics by coupled Josephson junction qubits. Considering a current-biased Josephson junction (CBJJ), we generate maximally entangled states. In particular, the entanglement dynamics is considered as a function of the decoherence parameters, such as the temperature, the ratio $r\equiv\omega_c/\omega_0$ between the reservoir cutoff frequency $\omega_c$ and the system oscillator frequency $\omega_0$, % between $\omega_0$ the characteristic frequency of the %quantum system of interest, and $\omega_c$ the cut-off frequency of %Ohmic reservoir and the energy levels split of the superconducting circuits in the non-Markovian master equation. We analyzed the entanglement sudden death (ESD) and entanglement sudden birth (ESB) by the non-Markovian master equation. Furthermore, we find that the larger the ratio $r$ and the thermal energy $k_BT$, the shorter the decoherence. In this superconducting qubit system we find that the entanglement can be controlled and the ESD time can be prolonged by adjusting the temperature and the superconducting phases $\Phi_k$ which split the energy levels.Comment: 13 pages, 3 figure

Preformation of clusters in heavy nuclei and cluster radioactivity

Within the preformed cluster model approach, the values of the preformation factors have been deduced from the experimental cluster decay half-lives assuming that the decay constant of the heavy-ion emission is the product of the assault frequency, the preformation factor and the penetrability. The law according to which the preformation factors follow a simple dependence on the mass of the cluster was confirmed. Then predictions for some most possible cluster decays are provided

Analytic expressions for alpha particle preformation in heavy nuclei

The experimental alpha decay energies and half-lives are investigated systematically to extract the alpha particle preformation in heavy nuclei. Formulas for the preformation factors are proposed. They can be used to guide the microscopic studies on preformation factors and perform accurate calculations of the alpha decay half-lives. There is little evidence for the existence of an island of long stability of superheavy nuclei (SHN)

Surface Properties of SiCp/Al Composite by Powder-Mixed EDM

AbstractThis paper uses a kind of moderate volume fraction (40%) of SiC particle reinforced Al matrix composites (SiCp/Al) to research how the surface properties are affected in conventional EDM (EDM) and powder-mixed EDM (PMEDM). By means of environment scanning electron microscope (ESEM) and HIT friction and wear tester, surface micro-topography, elements and wear resistance were analyzed. Experiments and researches indicate that compared with EDM, the surface properties machined by using PMEDM are improved greatly. The PMEDM surface roughness decreases about 31.5%; corrosion resistance is better too; and wear resistance is twice of EDM. Powder-mixed EDM has promising applications in metal matrix composites machining field