225 research outputs found

    A classical explanation of quantization

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    In the context of our recently developed emergent quantum mechanics, and, in particular, based on an assumed sub-quantum thermodynamics, the necessity of energy quantization as originally postulated by Max Planck is explained by means of purely classical physics. Moreover, under the same premises, also the energy spectrum of the quantum mechanical harmonic oscillator is derived. Essentially, Planck's constant h is shown to be indicative of a particle's "zitterbewegung" and thus of a fundamental angular momentum. The latter is identified with quantum mechanical spin, a residue of which is thus present even in the non-relativistic Schroedinger theory.Comment: 20 pages; version accepted for publication in Foundations of Physic

    Measurement of the 58Ni(α, γ) 62Zn reaction and its astrophysical impact

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    Funding Details: PHY 08-22648, NSF, National Science Foundation; PHY 0969058, NSF, National Science Foundation; PHY 1102511, NSF, National Science FoundationCross section measurements of the 58Ni(α,γ)62Zn reaction were performed in the energy range Eα=5.5to9.5 MeV at the Nuclear Science Laboratory of the University of Notre Dame, using the NSCL Summing NaI(Tl) detector and the γ-summing technique. The measurements are compared to predictions in the statistical Hauser-Feshbach model of nuclear reactions using the SMARAGD code. It is found that the energy dependence of the cross section is reproduced well but the absolute value is overestimated by the prediction. This can be remedied by rescaling the α width by a factor of 0.45. Stellar reactivities were calculated with the rescaled α width and their impact on nucleosynthesis in type Ia supernovae has been studied. It is found that the resulting abundances change by up to 5% when using the new reactivities. © 2014 American Physical Society.Peer reviewe

    Dual Magnetic Separator for TRIμ\muP

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    The TRIμ\muP facility, under construction at KVI, requires the production and separation of short-lived and rare isotopes. Direct reactions, fragmentation and fusion-evaporation reactions in normal and inverse kinematics are foreseen to produce nuclides of interest with a variety of heavy-ion beams from the superconducting cyclotron AGOR. For this purpose, we have designed, constructed and commissioned a versatile magnetic separator that allows efficient injection into an ion catcher, i.e., gas-filled stopper/cooler or thermal ionizer, from which a low energy radioactive beam will be extracted. The separator performance was tested with the production and clean separation of 21^{21}Na ions, where a beam purity of 99.5% could be achieved. For fusion-evaporation products, some of the features of its operation as a gas-filled recoil separator were tested.Comment: accepted by Nucl.Instr. Meth., final versio

    Expanding RIB Capabilities at the Cyclotron Institute: \textsuperscript{3}He-LIG production with an Isobar Separator LSTAR

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    A new \textsuperscript{3}He-driven IGISOL production station and mass separator have been designed to produce neutron-deficient low-mass isotopes at the Cyclotron Institute for the TAMUTRAP facility. The LSTAR design has a mass resolution M/ΔM≥3,000M/\Delta M\geq 3, 000 to reject contaminants with >95%\gt95\% efficiency.Comment: Proceeding for EMIS 202

    Modelación numérica hidrodinámico-hidrológica en zonas de inundación con presencia de infraestructura

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    Se presenta la modelación numérica computacional de la hidrodinámica superficial e hidrológica de la zona de estudio donde se pretende construir infraestructura para la exploración de hidrocarburos en las márgenes del río Grijalva, México; para ello se muestra el análisis de la información meteorológica, determinando los valores de intensidad de precipitación, temperaturas, evaporación y una estimación de los gastos, correspondiente al año 2014; las zonas de inundación se estimaron con el uso de programas desarrollados en Fortran y Matlab, que resuelven las ecuaciones de Navier-Stokes-Reynolds para flujos a superficie libre y la intensidad de precipitación con la distribución de Gumbel, con parámetros estimados mediante el método de Momentos Ponderados con Probabilidad (MPP), con los cuales, mediante una malla numérica de la topografía, en conjunto con los valores meteorológicos, como condiciones iniciales y forzantes, se determina la magnitud de la inundación del área de estudio, así como la obtención de gastos, velocidades y el funcionamiento hidráulico de las obras de mitigación propuestas para preservar el balance hidrológico del sistema

    The first direct measurement of ¹²C (¹²C,n) ²³Mg at stellar energies

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    Neutrons produced by the carbon fusion reaction ¹²C(¹²C,n)²³Mg play an important role in stellar nucleosynthesis. However, past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. We present the first direct measurement that extends deep into the astrophysical energy range along with a new and improved extrapolation technique based on experimental data from the mirror reaction ¹²C(¹²C,p)²³Na. The new reaction rate has been determined with a well-defined uncertainty that exceeds the precision required by astrophysics models. Using our constrained rate, we find that ¹²C(¹²C,n)²³Mg is crucial to the production of Na and Al in Pop-III Pair Instability Supernovae. It also plays a non-negligible role in the production of weak s-process elements as well as in the production of the important galacti

    Laplacian growth with separately controlled noise and anisotropy

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    Conformal mapping models are used to study competition of noise and anisotropy in Laplacian growth. For that, a new family of models is introduced with the noise level and directional anisotropy controlled independently. Fractalization is observed in both anisotropic growth and the growth with varying noise. Fractal dimension is determined from cluster size scaling with its area. For isotropic growth we find d = 1.7, both at high and low noise. For anisotropic growth with reduced noise the dimension can be as low as d = 1.5 and apparently is not universal. Also, we study fluctuations of particle areas and observe, in agreement with previous studies, that exceptionally large particles may appear during the growth, leading to pathologically irregular clusters. This difficulty is circumvented by using an acceptance window for particle areas.Comment: 13 pages, 15 figure
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