Resonance ionization spectroscopy of thorium isotopes - towards a laser spectroscopic identification of the low-lying 7.6 eV isomer of Th-229

In-source resonance ionization spectroscopy was used to identify an efficient and selective three step excitation/ionization scheme of thorium, suitable for titanium:sapphire (Ti:sa) lasers. The measurements were carried out in preparation of laser spectroscopic investigations for an identification of the low-lying Th-229m isomer predicted at 7.6 +- 0.5 eV above the nuclear ground state. Using a sample of Th-232, a multitude of optical transitions leading to over 20 previously unknown intermediate states of even parity as well as numerous high-lying odd parity auto-ionizing states were identified. Level energies were determined with an accuracy of 0.06 cm-1 for intermediate and 0.15 cm-1 for auto-ionizing states. Using different excitation pathways an assignment of total angular momenta for several energy levels was possible. One particularly efficient ionization scheme of thorium, exhibiting saturation in all three optical transitions, was studied in detail. For all three levels in this scheme, the isotope shifts of the isotopes Th-228, Th-229, and Th-230 relative to Th-232 were measured. An overall efficiency including ionization, transport and detection of 0.6 was determined, which was predominantly limited by the transmission of the mass spectrometer ion optics

IMPALAS: Investigation of MagnetoPause Activity using Longitudinally-Aligned Satellites—a mission concept proposed for the ESA M3 2020/2022 launch

The dayside magnetopause is the primary site of energy transfer from the solar wind into the magnetosphere, and modulates the activity observed within the magnetosphere itself. Specific plasma processes operating on the magnetopause include magnetic reconnection, generation of boundary waves, propagation of pressure-pulse induced deformations of the boundary, formation of boundary layers and generation of Alfvén waves and field-aligned current systems connecting the boundary to the inner magnetosphere and ionosphere. However, many of the details of these processes are not fully understood. For example, magnetic reconnection occurs sporadically, producing flux transfer events, but how and where these arise, and their importance to the global dynamics of the magnetospheric system remain unresolved. Many of these phenomena involve propagation across the magnetopause surface. Measurements at widely-spaced (Δ ˜ 5 RE) intervals along the direction of dayside terrestrial field lines at the magnetopause would be decisive in resolving these issues. We describe a mission carrying a fields and plasmas payload (including magnetometer, ion and electron spectrometer and energetic particle telescopes) on three identical spacecraft in synchronized orbits. These provide the needed separations, with each spacecraft skimming the dayside magnetopause and continuously sampling this boundary for many hours. The orbits are phased such that (i) all three spacecraft maintain common longitude and thus sample along the same magnetopause field line; (ii) the three spacecraft reach local midday when northern European ground-based facilities also lie near local midday, enabling simultaneous sampling of magnetopause field lines and their footprints

Exploring the potential of public proteomics data

In a global effort for scientific transparency, it has become feasible and good practice to share experimental data supporting novel findings. Consequently, the amount of publicly available MS-based proteomics data has grown substantially in recent years. With some notable exceptions, this extensive material has however largely been left untouched. The time has now come for the proteomics community to utilize this potential gold mine for new discoveries, and uncover its untapped potential. In this review, we provide a brief history of the sharing of proteomics data, showing ways in which publicly available proteomics data are already being (re-)used, and outline potential future opportunities based on four different usage types: use, reuse, reprocess, and repurpose. We thus aim to assist the proteomics community in stepping up to the challenge, and to make the most of the rapidly increasing amount of public proteomics data

On Petition for a Writ of Certiorari to The United States Court of Appeals for The Eighth Circuit, Brief of Law Professors Paul F. Rothstein, et. al., Office of the President v. Office of Independent Counsel

This Court should grant review not only because this is a case of national importance and prominence, but also because the decision below is a conspicuous departure from settled principles of evidence law. The panel majority concluded that communications between government lawyers and government officials are not protected by the attorney-client privilege, at least when those communications are sought by a federal grand jury. That conclusion conflicts with the predominant common-law understanding that the attorney-client privilege applies to government entities and that where the privilege applies, it is absolute (i.e., it protects against disclosure in all types of legal and investigative proceedings). In particular, the Court of Appeals\u27 decision rests on a fundamental misunderstanding of this Court\u27s decisions in Upjohn Co. v. United States, 449 U.S. 383 (1981), and United States v. Nixon, 418 U.s. 683 (1974). Moreover, this case warrants further review because the decision below has profound implications beyond the parties to this dispute. The Court of Appeals\u27 ruling, if allowed to stand, will create widespread uncertainty among federal, state, and local officials concerning the extent to which their communications with their agency lawyers, for the purpose of seeking legal advice in the conduct of governmental affairs, are protected by the attorney-client privilege. Unless this Court grants review and resolves this uncertainty, the decision below will likely have an adverse effect on the current and future operation of not only the Office of the President of the United States, but also government at all levels. At the very least, a decision of such vast implications (as in the present case) should be made by the highest court in the land. We accordingly urge the Court to grant the petition for review

Magnetosphere-Ionosphere Coupling Through E-region Turbulence: Anomalous Conductivities and Frictional Heating

Global magnetospheric MHD codes using ionospheric conductances based on laminar models systematically overestimate the cross-polar cap potential during storm time by up to a factor of two. At these times, strong DC electric fields penetrate to the E region and drive plasma instabilities that create turbulence. This plasma density turbulence induces non-linear currents, while associated electrostatic field fluctuations result in strong anomalous electron heating. These two effects will increase the global ionospheric conductance. Based on the theory of non-linear currents developed in the companion paper, this paper derives the correction factors describing turbulent conductivities and calculates turbulent frictional heating rates. Estimates show that during strong geomagnetic storms the inclusion of anomalous conductivity can double the total Pedersen conductance. This may help explain the overestimation of the cross-polar cap potentials by existing MHD codes. The turbulent conductivities and frictional heating presented in this paper should be included in global magnetospheric codes developed for predictive modeling of space weather.Comment: 13 pages, 5 figures, 2nd of two companion paper

Precision mass measurements of magnesium isotopes and implications on the validity of the Isobaric Mass Multiplet Equation

If the mass excess of neutron-deficient nuclei and their neutron-rich mirror partners are both known, it can be shown that deviations of the Isobaric Mass Multiplet Equation (IMME) in the form of a cubic term can be probed. Such a cubic term was probed by using the atomic mass of neutron-rich magnesium isotopes measured using the TITAN Penning trap and the recently measured proton-separation energies of $^{29}$Cl and $^{30}$Ar. The atomic mass of $^{27}$Mg was found to be within 1.6$\sigma$ of the value stated in the Atomic Mass Evaluation. The atomic masses of $^{28,29}$Mg were measured to be both within 1$\sigma$, while being 8 and 34 times more precise, respectively. Using the $^{29}$Mg mass excess and previous measurements of $^{29}$Cl we uncovered a cubic coefficient of $d$ = 28(7) keV, which is the largest known cubic coefficient of the IMME. This departure, however, could also be caused by experimental data with unknown systematic errors. Hence there is a need to confirm the mass excess of $^{28}$S and the one-neutron separation energy of $^{29}$Cl, which have both come from a single measurement. Finally, our results were compared to ab initio calculations from the valence-space in-medium similarity renormalization group, resulting in a good agreement.Comment: 7 pages, 3 figure

Three-dimensional magnetic flux rope structure formed by multiple sequential X-line reconnection at the magnetopause

On 14 June 2007, four Time History of Events and Macroscale Interactions during Substorms spacecraft observed a flux transfer event (FTE) on the dayside magnetopause, which has been previously proved to be generated by multiple, sequential X-line reconnection (MSXR) in a 2-D context. This paper reports a further study of the MSXR event to show the 3-D viewpoint based on additional measurements. The 3-D structure of the FTE flux rope across the magnetospheric boundary is obtained on the basis of multipoint measurements taken on both sides of the magnetopause. The flux rope's azimuthally extended section is found to lie approximately on the magnetopause surface and parallel to the X-line direction; while the axis of the magnetospheric branch is essentially along the local unperturbed magnetospheric field lines. In the central region of the flux rope, as distinct from the traditional viewpoint, we find from the electron distributions that two types of magnetic field topology coexist: opened magnetic field lines connecting the magnetosphere and the magnetosheath and closed field lines connecting the Southern and Northern hemispheres. We confirm, therefore, for the first time, the characteristic feature of the 3-D reconnected magnetic flux rope, formed through MSXR, through a determination of the field topology and the plasma distributions within the flux rope. Knowledge of the complex geometry of FTE flux ropes will improve our understanding of solar wind-magnetosphere interaction.Astronomy & AstrophysicsSCI(E)5ARTICLE51904-191111