920 research outputs found

    Processinvändningarna enligt finsk allmän civilprocessrätt

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    Akademisk afhandling af Rabbe Axel Wrede, J. U. D:R, V. Häradshövding. Framställes med tillstånd af Juridiska fakulteten vid Kejserliga Alexanders Universitetet i Finland till offentlig granskning i Hist-fil. auditoriet den 29 Maj 1884 kl. 10 f. m

    Experimental evidence of a natural parity state in 26^{26}Mg and its impact to the production of neutrons for the s process

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    We have studied natural parity states in 26^{26}Mg via the 22^{22}Ne(6^{6}Li,d)26^{26}Mg reaction. Our method significantly improves the energy resolution of previous experiments and, as a result, we report the observation of a natural parity state in 26^{26}Mg. Possible spin-parity assignments are suggested on the basis of published γ\gamma-ray decay experiments. The stellar rate of the 22^{22}Ne(α\alpha,γ\gamma)26^{26}Mg reaction is reduced and may give rise to an increase in the production of s-process neutrons via the 22^{22}Ne(α\alpha,n)25^{25}Mg reaction.Comment: Published in PR

    Production of 26Al in stellar hydrogen-burning environments: spectroscopic properties of states in 27Si

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    Model predictions of the amount of the radioisotope 26Al produced in hydrogen-burning environments require reliable estimates of the thermonuclear rates for the 26gAl(p,{\gamma})27Si and 26mAl(p,{\gamma})27Si reactions. These rates depend upon the spectroscopic properties of states in 27Si within about 1 MeV of the 26gAl+p threshold (Sp = 7463 keV). We have studied the 28Si(3He,{\alpha})27Si reaction at 25 MeV using a high-resolution quadrupole-dipole-dipole-dipole magnetic spectrograph. For the first time with a transfer reaction, we have constrained J{\pi} values for states in 27Si over Ex = 7.0 - 8.1 MeV through angular distribution measurements. Aside from a few important cases, we generally confirm the energies and spin-parity assignments reported in a recent {\gamma}-ray spectroscopy study. The magnitudes of neutron spectroscopic factors determined from shell-model calculations are in reasonable agreement with our experimental values extracted using this reaction.Comment: accepted for publication in Phys. Rev.

    The 21Na(p,gamma)22Mg Reaction and Oxygen-Neon Novae

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    The 21Na(p,gamma)22Mg reaction is expected to play an important role in the nucleosynthesis of 22Na in Oxygen-Neon novae. The decay of 22Na leads to the emission of a characteristic 1.275 MeV gamma-ray line. This report provides the first direct measurement of the rate of this reaction using a radioactive 21Na beam, and discusses its astrophysical implications. The energy of the important state was measured to be Ec.m._{c.m.}= 205.7 ±\pm 0.5 keV with a resonance strength ωγ=1.03±0.16stat±0.14sys\omega\gamma = 1.03\pm0.16_{stat}\pm0.14_{sys} meV.Comment: Accepted for publication in Physical Review Letter

    Shell-model studies of the astrophysical rp -process reactions S 34 (p,Îł) Cl 35 and Cl 34g,m (p,Îł) Ar 35

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    © 2020 American Physical Society. Background: Dust grains condensed in the outflows of presolar classical novae should have been present in the protosolar nebula. Candidates for such presolar nova grains have been found in primitive meteorites and can in principle be identified by their isotopic ratios, but the ratios predicted by state-of-the-art one-dimensional hydrodynamic models are uncertain due to nuclear-physics uncertainties. Purpose: To theoretically calculate the thermonuclear rates and uncertainties of the S34(p,γ)Cl35 and Cl34g,m(p,γ)Ar35 reactions and investigate their impacts on the predicted S34/S32 isotopic ratio for presolar nova grains. Method: A shell-model approach in a (0+1) ħω model space was used to calculate the properties of resonances in the S34(p,γ)Cl35 and Cl34g,m(p,γ)Ar35 reactions and their thermonuclear rates. Uncertainties were estimated using a Monte Carlo method. The implications of these rates and their uncertainties on sulfur isotopic nova yields were investigated using a postprocessing nucleosynthesis code. The rates for transitions from the ground state of Cl34 as well as from the isomeric first excited state of Cl34 were explicitly calculated. Results: At energies in the resonance region near the proton-emission threshold, many negative-parity states appear. Energies, spectroscopic factors, and proton-decay widths are reported. The resulting thermonuclear rates are compared with previous determinations. Conclusions: The shell-model calculations alone are sufficient to constrain the variation of the S34/S32 ratios to within about 30%. Uncertainties associated with other reactions must also be considered, but in general we find that the S34/S32 ratios are not a robust diagnostic to clearly identify presolar grains made from nova ejecta

    Weak Interaction Studies with 6He

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    The 6He nucleus is an ideal candidate to study the weak interaction. To this end we have built a high-intensity source of 6He delivering ~10^10 atoms/s to experiments. Taking full advantage of that available intensity we have performed a high-precision measurement of the 6He half-life that directly probes the axial part of the nuclear Hamiltonian. Currently, we are preparing a measurement of the beta-neutrino angular correlation in 6He beta decay that will allow to search for new physics beyond the Standard Model in the form of tensor currents.Comment: 5 pages, 4 figures, proceedings for the Eleventh Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2012
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