The LHCb upgrade I

The LHCb upgrade represents a major change of the experiment. The detectors have been almost completely renewed to allow running at an instantaneous luminosity five times larger than that of the previous running periods. Readout of all detectors into an all-software trigger is central to the new design, facilitating the reconstruction of events at the maximum LHC interaction rate, and their selection in real time. The experiment's tracking system has been completely upgraded with a new pixel vertex detector, a silicon tracker upstream of the dipole magnet and three scintillating fibre tracking stations downstream of the magnet. The whole photon detection system of the RICH detectors has been renewed and the readout electronics of the calorimeter and muon systems have been fully overhauled. The first stage of the all-software trigger is implemented on a GPU farm. The output of the trigger provides a combination of totally reconstructed physics objects, such as tracks and vertices, ready for final analysis, and of entire events which need further offline reprocessing. This scheme required a complete revision of the computing model and rewriting of the experiment's software

Wedge equilibrium in fold-and-thrust belts: prediction of out-of-sequence thrusting based on sandbox experiments and natural examples

Thrust tectonics are dealt with on the basis of primarily experiments focusing on the dynamics of a developing thrust belt and on understanding and predicting normal-sequence and out-of-sequence thrusting. Field examples are presented in addition to the examples of sandbox-model experiments. The results have improved the insight into thrust-belt-forming mechanisms; the validity of the conclusions is supported by natural examples. The experimental program was aimed at examining the effect of changes in a selection of key parameters in thrust tectonics on the geometry and the successive phases in the development of thrust sheets. Sandbox experiments were used to analyse the effects of basal friction, detachment lithology, basement relief and syntectonic sedimentation. Multilayer experiments were performed to simulate the effects of ductile detachment lithologies. It was found that a thrust belt’s cross-sectional geometry is formed in a dynamic process during which the wedge may develop from subcritical through critical to supercritical and back to critical again.The process is illustrated with sandbox experiments, analysed by time-lapse computed tomography scans and in-situ stress measurements. On the basis of the sandboxmodel results and the natural examples, we conclude that a critical examination of the boundary conditions of a fold-andthrust belt and of changes in these conditions during the deformation process enables predictions about the geometry and kinematics of the thrust belt

Analogue modelling of a reactivated, basement controlled strike-slip zone, Sierra de Albarracín, Spain: application of sandbox modelling to polyphase deformation

This paper presents the results of an analogue modelling study on the reactivation of Riedel shears generated by basement-induced sinistral strike-slip faulting. It is based on a natural example in the Sierra de Albarracín, Iberian Range (Spain). The area has a polyphase deformation history, defined by the Variscan and Alpine orogenies. Late Variscan deformation was concentrated in a wide NW-SE shear zone with accompanying kilometre-scale E-W Riedel shears, which divided the Palaeozoic basement into large fault blocks. Alpine reactivation resulted in differential movements on the Riedel shears, as evidenced by a NW-SE chain of Palaeozoic inliers surrounded by a Mesozoic cover that generally shows minor deformations except near the E-W Riedel shears, where strata locally appear in near-vertical to overturned position. Sandbox analogue modelling was applied to improve insight into the structural history. It focused on the kinematics of spontaneously developed en echelon Riedel shears, reactivated in a rotated stress field. Sand with a controlled added strength was used to form Riedel shears in a first deformation phase to act as weak zones for a second phase. The modelling showed that in the first deformation phase large pop-up structures developed between the Riedel shears in a basement-induced sinistral strike-slip zone. Later reactivation in the N060°E and N135°E shortening directions was taken up respectively by sinistral-reverse and dextral-reverse shear along the pre-existing Riedel shears, but only if the sand on one side of the fault zone was allowed to move freely along the other. Scissor faulting along the Riedel shears with their complex 3D-geometry increased the height of the up-squeezed blocks. For experiments with fixed boundaries and no oil-water emulsion layer between the base plate and sand pack, thrusting at the backstop occurred rather than reactivation of the Riedel shears. This approach provided robust insights on the 4D development of the Sierra de Albarracín area. © The Geological Society of London 2006

Data assimilation of PS-InSAR movement measurements applied to the bergermeer gas field

This paper reports a study on the use of satellite radar data to constrain the subsurface model parameters of the Bergermeer gas field. Using PSI (Persistent Scatterer InSAR) technology, ascending and descending data were applied in line-of-sight geometry, i.e., without first unravelling the horizontal and vertical components of the signal. The model parameters were constrained using an ensemble smoother with multiple data assimilation. A good match could be obtained with realistic values of the reservoir compaction coefficient and of the subsurface basement elastic modulus. For the aquifer parts that were depleted according to the reservoir simulation, the northern part indeed gave a reasonable value for the compaction coefficient. For the southern part the resulting compaction coefficient was around zero, indicating that the pressure depletion in this part of the aquifer was overestimated and that it was actually not connected to the reservoir. The study shows that it is feasible to use PSI surface movement data to obtain information about the reservoir and that the use of line-of-sight movements from both ascending and descending satellite passes adds an additional dimension to the data and an improved quality of the assimilation results

Application of an ensemble smoother with multiple data assimilation to the Bergermeer gas field, using PS-InSAR

Satellite radar data were used to estimate subsurface model parameters of the Bergermeer gas field. Directly using combinations of the line-of-sight measurements in both ascending and descending satellite geometry provided an additional dimension in the data and avoided the introduction of errors during interpolation to horizontal and vertical movements. The model parameters were constrained using an Ensemble Smoother with Multiple Data Assimilation. A good match was obtained, with realistic values for the reservoir compaction coefficient and of the subsurface elastic moduli. The resulting compaction coefficients for the aquifers were interpreted with the use of geologic and reservoir knowledge: we concluded that the aquifers furthest away from the gas field were not connected to the reservoir. © 2015 Elsevier Ltd