Photoionization Cross-Sections of Carbon-Like N+ Near the K-Edge (390–440 eV)

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398–403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415–440 eV photon region 1s⟶(1s2s22p2 4P)np and 1s⟶(1s2s22p2 2P)np resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

Photoionization Cross Sections of Carbon-Like N+ near the K-Edge (390 eV - 440 eV)

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398 eV - 403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415 eV - 440 eV photon region 1s⟶1s2s22p2 4Pnp and 1s⟶1s2s22p2 2Pnp resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

GIANT M1 RESONANCE ON THE GROUND AND EXCITED STATES IN 2s1d-SHELL NUCLEI

The gamma decay of the resonance-like structures observed in the reaction of radiative capture of protons by the nuclei 22Ne, 26Mg, 30Si, 34,36S, and 38Ar in the region of excitation energies of 7…12 MeV was studied. The excitation functions of this reaction were measured. The resonance strengths in the energy range of the accelerated protons Ep = 1.0…3.0 MeV were determined. The obtained discrete distributions of the magnetic dipole γ-transitions on the ground and excited states for the nuclei of the 2s1d-shell have resonance character. Giant M1 resonance on the ground and excited states in the 23Na, 27Al, 31P, 35.37Cl, and 39K nuclei has been identified. The position of the M1 resonance on excited states coincides with that predicted by the Brink-Axel hypothesis for nuclei that are at the beginning of the subshell.

Free Core Resonance parameters from diurnal strain tides recorded by the Gran Sasso (Italy) and Canfranc (Spain) underground geodetic interferometers

<p>The Free Core Nutation (FCN) is a retrograde mode related to the slight misalignment of the rotation axis of the fluid outer core and the elastic mantle, with a period of about 430 sidereal days in the celestial frame. In the Earth-fixed reference frame, the (complex) frequency of the Free Core Nutation (FCN) is inside the diurnal tidal band and causes a resonant response (Free Core Resonance, FCR) of some diurnal tidal waves to the tide-generating forces.<br>The FCN is usually investigated through its effects on gravity tides and Earth nutations. Here we analyse about 7 years of discontinuous strain records from two 90-m long laser interferometers (strainmeters) operating under the Gran Sasso (Italy) massif and about 4.6 years of discontinuous strain records from two 70-m-long laser interferometers operating the Central Pyrenees (Spain).<br>Starting from the expressions for the vector displacements due to diurnal and semi-diurnal solid tides, we express  extension along any azimuthal direction in terms of three complex parameters (related to areal strain and the two shear strain components), which are functions of the latitude-dependent Love and Shida numbers. Those three complex parameters are affected by the FCR through three complex resonance strengths.<br>We find that we can infer 4 model parameters from the inversion of our data, i. e. from the comparison between amplitudes and phases of the measured and theoretical diurnal tides close to the resonance: the FCN period, the FCR quality factor, the imaginary part of one of the three resonance strengths, and the real part of another resonance strength. However, local deformation is distorted with respect to regional deformation because of siting effects. Coupling between local extension (measured by the interferometers) and regional deformation can be described by three coupling coefficients per interferometer, thus introducing 12 additional unknown in the inversions.<br>We minimize misfit between amplitudes and phases of the measured and theoretical tidal strain jointly for all the interferometers by sampling the 4D model parameter space, while optimal coupling coefficients for each interferometer are computed through a simple matrix inversion at each sampled point.<br>Theoretical strain tides is corrected for the effects of the water load oscillations caused by ocean tides. We use FES2014 and TPXO9 ocean models, while the appropriate Earth model for different ocean load areas is chosen basing on the widths of the continental shelves nearby the stations and the inversion misfits.<br>Although we analyse records from two stations only and the amount of data is relatively small, our results for the FCN period and (to some extent) the FCR quality factor are robust and comparable to those obtained from gravity tides and  nutations. Moreover, we obtain reliable values of the resonance strengths and robust estimates of the coupling coefficients for all the interferometers.</p>