Experience with the Open Source based implementation for ATLAS Conditions Data Management System

Conditions Data in high energy physics experiments is frequently seen as every data needed for reconstruction besides the event data itself. This includes all sorts of slowly evolving data like detector alignment, calibration and robustness, and data from detector control system. Also, every Conditions Data Object is associated with a time interval of validity and a version. Besides that, quite often is useful to tag collections of Conditions Data Objects altogether. These issues have already been investigated and a data model has been proposed and used for different implementations based in commercial DBMSs, both at CERN and for the BaBar experiment. The special case of the ATLAS complex trigger that requires online access to calibration and alignment data poses new challenges that have to be met using a flexible and customizable solution more in the line of Open Source components. Motivated by the ATLAS challenges we have developed an alternative implementation, based in an Open Source RDBMS. Several issues were investigated land will be described in this paper: -The best way to map the conditions data model into the relational database concept considering what are foreseen as the most frequent queries. -The clustering model best suited to address the scalability problem. -Extensive tests were performed and will be described. The very promising results from these tests are attracting the attention from the HEP community and driving further developments.Comment: 8 pages, 4 figures, 3 tables, conferenc

Dynamics and stability of Bose-Einstein solitons in tilted optical lattices

Bloch oscillations of Bose-Einstein condensates realize sensitive matter-wave interferometers. We investigate the dynamics and stability of bright-soliton wave packets in one-dimensional tilted optical lattices with a modulated mean-field interaction $g(t)$. By means of a time-reversal argument, we prove the stability of Bloch oscillations of breathing solitons that would be quasistatically unstable. Floquet theory shows that these breathing solitons can be more stable against certain experimental perturbations than rigid solitons or even non-interacting wave packets.Comment: final, published versio

Counter-rotation in relativistic magnetohydrodynamic jets

Young stellar object observations suggest that some jets rotate in the opposite direction with respect to their disk. In a recent study, Sauty et al. (2012) have shown that this does not contradict the magnetocentrifugal mechanism that is believed to launch such outflows. Signatures of motions transverse to the jet axis and in opposite directions have recently been measured in M87 (Meyer et al. 2013). One possible interpretation of this motion is the one of counter rotating knots. Here, we extend our previous analytical derivation of counter-rotation to relativistic jets, demonstrating that counter-rotation can indeed take place under rather general conditions. We show that both the magnetic field and a non-negligible enthalpy are necessary at the origin of counter-rotating outflows, and that the effect is associated with a transfer of energy flux from the matter to the electromagnetic field. This can be realized in three cases : if a decreasing enthalpy causes an increase of the Poynting flux, if the flow decelerates, or, if strong gradients of the magnetic field are present. An illustration of the involved mechanism is given by an example of relativistic MHD jet simulation.Comment: Accepted for publication in ApJ

Cosmological constant constraints from observation-derived energy condition bounds and their application to bimetric massive gravity

Among the various possibilities to probe the theory behind the recent accelerated expansion of the universe, the energy conditions (ECs) are of particular interest, since it is possible to confront and constrain the many models, including different theories of gravity, with observational data. In this context, we use the ECs to probe any alternative theory whose extra term acts as a cosmological constant. For this purpose, we apply a model-independent approach to reconstruct the recent expansion of the universe. Using Type Ia supernova, baryon acoustic oscillations and cosmic-chronometer data, we perform a Markov Chain Monte Carlo analysis to put constraints on the effective cosmological constant $\Omega^0_{\rm eff}$. By imposing that the cosmological constant is the only component that possibly violates the ECs, we derive lower and upper bounds for its value. For instance, we obtain that $0.59 < \Omega^0_{\rm eff} < 0.91$ and $0.40 < \Omega^0_{\rm eff} < 0.93$ within, respectively, $1\sigma$ and $3\sigma$ confidence levels. In addition, about 30\% of the posterior distribution is incompatible with a cosmological constant, showing that this method can potentially rule it out as a mechanism for the accelerated expansion. We also study the consequence of these constraints for two particular formulations of the bimetric massive gravity. Namely, we consider the Visser's theory and the Hassan and Roses's massive gravity by choosing a background metric such that both theories mimic General Relativity with a cosmological constant. Using the $\Omega^0_{\rm eff}$ observational bounds along with the upper bounds on the graviton mass we obtain constraints on the parameter spaces of both theories.Comment: 11 pages, 4 figures, 1 tabl

CAVITATION EROSION MICRO-JETS STUDIES OF ALUMINUM SPECIMENS WITH THE AID OF THE COMPACT ROTATING DISK DEVICE

The shape of micro-jets created in the final stages of cavities collapses are studied here with the goal to explain the shape of the pits, formed on the surface of commercial aluminum specimens.These marks on the specimen surfaces are obtained experimentally with the aid of the compact rotating disk device and a scanning electronic microscope. Some explain is attempt, based on the theories of the potential flow and forms

Constraints on Cold Dark Matter Accelerating Cosmologies and Cluster Formation

We discuss the properties of homogeneous and isotropic flat cosmologies in which the present accelerating stage is powered only by the gravitationally induced creation of cold dark matter (CCDM) particles ($\Omega_{m}=1$). For some matter creation rates proposed in the literature, we show that the main cosmological functions such as the scale factor of the universe, the Hubble expansion rate, the growth factor and the cluster formation rate are analytically defined. The best CCDM scenario has only one free parameter and our joint analysis involving BAO + CMB + SNe Ia data yields ${\tilde{\Omega}}_{m}= 0.28\pm 0.01$ ($1\sigma$) where $\tilde{{\Omega}}_{m}$ is the observed matter density parameter. In particular, this implies that the model has no dark energy but the part of the matter that is effectively clustering is in good agreement with the latest determinations from large scale structure. The growth of perturbation and the formation of galaxy clusters in such scenarios are also investigated. Despite the fact that both scenarios may share the same Hubble expansion, we find that matter creation cosmologies predict stronger small scale dynamics which implies a faster growth rate of perturbations with respect to the usual $\Lambda$CDM cosmology. Such results point to the possibility of a crucial observational test confronting CCDM with $\Lambda$CDM scenarios trough a more detailed analysis involving CMB, weak lensing, as well as the large scale structure.Comment: 12 pages, 3 figures, Accepted for publication by Physical Rev.