Electron-impact broadening of the 3s-3p lines in low-Z Li-like ions

The collisional electron-impact line widths of the 3s-3p transitions in Li-like ions from B III to Ne VIII are calculated with the convergent close-coupling (CCC) method from the atomic collision theory. The elastic and inelastic contributions to the line broadening and their Z-scaling are discussed in detail, and comparisons with recent experimental and theoretical results are also presented. It is found that similar to our previous study of line broadening in Be-like ions, the difference between experimental and CCC results monotonically increases with the spectroscopic charge of an ion.Comment: 23 pages, 8 figures, 1 table. To be published in JQSR

Filosofia della storia e teodicea

Il presente lavoro prende le mosse dalla celebre frase conclusiva delle Lezioni sulla filosofia della storia di Hegel: «Che, in mezzo ai mutevoli spettacoli delle sue storie, la storia mondiale sia proprio codesta evoluzione e il divenire reale dello spirito, ebbene questa è la vera teodicea, la giustificazione di Dio nella storia. Soltanto questa cognizione può conciliare lo spirito con la storia mondiale e con la realtà, il vedere che quanto è accaduto e accade tutti i giorni non è senza Dio, ma è in essenza l’opera di Dio stesso». A partire da tale spunto questa tesi è stata strutturata tematicamente per analizzare le posizioni di autori come Leibniz, Linnè e Kant, i quali costituiscono il nucleo centrale della presente analisi, e per mettere a confronto le loro teorie con quelle di altri grandi studiosi del passato come Rousseau, Adam Smith e Mandeville. Ovviamente non è possibile prescindere dalla componente morale degli scritti di questi filosofi, la quale è fondamentale per delimitare il campo d’indagine. Partendo dalla filosofia della storia come problema l’obiettivo della presente dissertazione è stato quello di contestualizzare tale questione in rapporto con la teodicea all’interno del pensiero degli autori individuati e, in particolare, di mettere in risalto le implicazioni che sottostanno alla base del rapporto tra uomo, Dio e natura. I testi di riferimento, oltre alle Lezioni sulla filosofia della storia (trad. it. a c. di G. Bonacina e L. Sichirollo, Roma-Bari, Laterza, 2008), sono i Saggi di Teodicea (Intr. di G. Cantelli, trad. it. a c. di M. Marilli, Milano, BUR, 2007) e la Confessio Philosophi (in Confessio Philosophi e altri scritti, trad. it. a c. di F. Piro, Napoli, Cronopio, 1992) di Leibniz, la Nemesis Divina (intr. e tr. inglese a c. di M.J. Petry, Dordrecht, Kluver Academic Publisher, 2001) di Carl Von Linné e lo scritto Sul fallimento di tutti i tentativi filosofici in Teodicea (in Scritti sul criticismo, trad. it. a c. di G. De Flaviis, Roma-Bari, Laterza, 1991). Alcune delle domande che nascono spontanee analizzando queste problematiche e alle quali si è cercato di dare una risposta sono le seguenti: secondo quali principi possiamo catalogare l’uomo come superiore agli altri animali, in quanto egli si riconosce come il fine della creazione? Per quale motivo Dio ha permesso l’esistenza del male al mondo? E come far coincidere l’assunto dell’uomo riguardo al mondo naturale in rapporto con la propria consapevolezza religiosa e morale? Come e quanto è cambiato l’uomo durante il passaggio dallo stato di natura allo stato civile

Electron Collisional Broadening of Isolated Lines from Multiply-Ionized Atoms

Recent experimental and theoretical (both improved semiclassical and fully quantum-mechanical) results for B III and Ne VII delta n = 0 transitions with n = 2 or 3, respectively, are discussed. The probable reasons for disagreements by about a factor of 2 between the fully quantum-mechanically calculated and both measured and semiclassically calculated widths can be explained in terms of violation of validity criteria and non-thermal Doppler effects. More independent determinations of line widths for multiply-ionized non-hydrogenic ions are called for, but meanwhile caution should be exercised in the use of corresponding semiclassically calculated widths, e.g., in opacity calculations or for plasma density diagnostics. Only the quantum calculations allow a clear separation of elastic and inelastic scattering contributions to the width. For B III, elastic scattering contributes about 30% whereas for Ne VII inelastic scattering dominates. This allows rather direct comparisons with benchmark electron-ion scattering experiments.Comment: 13 pages, PostScript only. To appear in JQSR

Hypernetted chain calculations for two-component plasmas

We have performed HNC calculations for dense beryllium plasma as studied experimentally using x-ray Thomson scattering, recently. We treated non-equilibrium situations with different electron and ion temperatures which are relevant in pump-probe experiments on ultra-short time scales. To consider quantum effects adequately, we used effective pair potentials to describe the interactions. Results are compared with classical as well as quantum corrected Debye model calculations.Comment: 7 pages, 4 figures. Contribution to the 12th International Workshop on the Physics of Non-Ideal Plasmas PNP 12, Sept. 4 - 8, 2006, Darmstadt, Germany. To appear in Contrib. Plasma Phy

Stark Broadening of the B III 2s-2p Lines

We present a quantum-mechanical calculation of Stark line widths from electron-ion collisions for the $2s_{1/2}-2p_{1/2,3/2}$, lambda = 2066 and 2067 A, resonance transitions in B III. The results confirm the previous quantum-mechanical R-matrix calculations but contradict recent measurements and semi-classical and some semi-empirical calculations. The differences between the calculations can be attributed to the dominance of small L partial waves in the electron-atom scattering, while the large Stark widths inferred from the measurements would be substantially reduced if allowance is made for hydrodynamic turbulence from high Reynolds number flows and the associated Doppler broadening.Comment: 21 pages, 4 figures; to be published in Phys. Rev.

X-ray Thomson Scattering from Dense Plasmas

Advances in the development of laser-produced x-ray sources have enabled a new class of high-energy density physics experiments. Powerful narrow-bandwidth x rays penetrate through short-lived hot dense states of matter and probe the physical properties with spectrally resolved x-ray scattering. Experiments from isochorically-heated plasmas with electron densities in the range of solid density and above have been demonstrated allowing for the first time exploration of the microscopic properties of dense matter regime close to strongly-coupled and Fermi degenerate conditions. Backscatter measurements have accessed the non-collective Compton scattering regime, which provides accurate diagnostic information on the temperature, density and ionization states. The forward scattering spectrum has been shown to measure the collective plasmon oscillations. Besides extracting the standard plasma parameters, density and temperature, forward scattering yields new observables such as a direct measure of collisions, quantum effects and detailed balance. In this talk, we will discuss new results important for applications of this technique for novel experiments in a wide range of research areas such as inertial confinement fusion, radiation-hydrodynamics, material science, and laboratory astrophysics

Probing the hydrogen melting line at high pressures by dynamic compression

We investigate the capabilities of dynamic compression by intense heavy ion beams to yield information about the high pressure phases of hydrogen. Employing ab initio simulations and experimental data, a new wide range equation of state for hydrogen is constructed. The results show that the melting line up to its maximum as well as the transition from molecular fluids to fully ionized plasmas can be tested with the beam parameters soon to be available. We demonstrate that x-ray scattering can distinguish between phases and dissociation states

X-ray spectroscopy from fusion plasmas

Our understanding of laser energy coupling into laser-driven inertial confinement fusion targets largely depends on our ability to accurately measure and simulate the plasma conditions in the underdense corona and in high density capsule implosions. X-ray spectroscopy is an important technique which has been applied to measure the total absorption of laser energy into the fusion target, the fraction of laser energy absorbed by hot electrons, and the conditions in the fusion capsule in terms of density and temperature. These parameters provide critical benchmarking data for performance studies of the fusion target and for radiation-hydrodynamic and laser-plasma interaction simulations. Using x-ray spectroscopic techniques for these tasks has required its application to non-standard conditions where kinetics models have not been extensively tested. In particular, for the conditions in high density implosions, where electron temperatures achieve 1 - 2 keV and electron densities reach 1024 cm-3 evolving on time scales of 21 cm-3 and which am independently diagnosed with Thomson scattering and stimulated Raman scattering. We find that kinetics modeling is in good agreement with measured intensities of the dielectronic satellites of the He-{beta} line (n= l-3) of Ar XVII. Applying these findings to the experimental results of capsule implosions provides additional evidence of� temperature gradients at peak compression