Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

We propose a new method for detecting high frequency gravitational waves (GWs) using high energy pulsed lasers. Through the inverse Gertsenshtein effect, the interaction between a GW and the laser beam results in the creation of an electromagnetic signal. The latter can be detected using single-photon counting techniques. We compute the minimal strain of a detectable GW which only depends on the laser parameters. We find that a resonance occurs in this process when the frequency of the GW is twice the frequency of the laser. With this method, the frequency range $10^{13}-10^{19} $ Hz is explored non-continuously for strains $h \gtrsim 10^{-20}$ for current laser systems and can be extended to $h \gtrsim 10^{-26}$ with future generation facilities.

Abstract:

The advent of x-ray free-electron lasers has enabled a range of new experimental investigations into the properties of matter driven to extreme conditions via intense x-ray-matter interactions. The femtosecond timescales of these interactions lead to the creation of transient high-energy-density plasmas, where both the electrons and the ions may be far from local thermodynamic equilibrium. Predictive modelling of such systems remains challenging because of the different timescales at which electrons and ions thermalize, and because of the vast number of atomic configurations required to describe highly-ionized plasmas. Here we present CCFLY, a code designed to model the time-dependent evolution of both electron distributions and ion states interacting with intense x-ray fields on ultra-short timescales, far from local thermodynamic equilibrium. We explore how the plasma relaxes to local thermodynamic equilibrium on femtosecond timescales in terms of the charge state distribution, electron density, and temperature.

Abstract:

In this paper, taking start from some verses of the Aeneid, the Author will focus on some literary and epigraphic documents in search for evidence of the geographical and ethnic references in Virgilian poem. In particular, there will be taken into account the passages and inscriptions which celebrate Rome's territorial expansionism and her dominion up to the borders of the known world thanks to Augustus, as the prince himself proudly declares in the chapter 26 of his Res gestae. The paper is structured in three sections: 1. Prophecies and divine promises in the Aeneid. 2. Possible historical references in the Aeneid. 3. Possible historical evidence in Latin inscriptions. In none of the other Latin poets active in the decade between 30 and 20 BC we find so frequent and explicit references to the military glories of Augustan Rome, with so many citations of peoples, lands, rivers and seas. This could not be conventional: if the historical references present in the Aeneid actually recall historical events, then the portrait of Virgil as a singer of Augustus' praises would be strengthened, and the utilitarian character of Roman poetry would be confirmed.