Constraining CP violation in neutral meson mixing with theory input

There has been a lot of recent interest in the experimental hints of CP violation in B_{d,s}^0 mixing, which would be a clear signal of beyond the standard model physics (with higher significance). We derive a new relation for the mixing parameters, which allows clearer interpretation of the data in models in which new physics enters in M_12 and/or \Gamma_12. Our results imply that the central value of the D\O\ measurement of the semileptonic CP asymmetry in B_{d,s}^0 decay is not only in conflict with the standard model, but in a stronger tension with data on \Delta\Gamma_s than previously appreciated. This result can be used to improve the constraint on \Delta\Gamma or A_SL, whichever is less precisely measured.Comment: 5 pages, 2 figures, informed of prior derivation of eq. (21), title modifie

Impact of the First Powering Cycles on the LHC Superconducting Dipole Coil Geometry

The impact of the first powering cycles on the LHC superconducting dipoles coil geometry has been investigated. Dedicated magnetic measurements have been performed to estimate the changes in the geometric component of the harmonics, caused by the last highest Lorentz force the coil has ever experienced. Several magnets have been powered at increasing current steps while the field quality has been measured to quantify the changes in geometry. The effect of the thermal cycles has been also considered as well as the systematic differences between measurements before and after the quench training. The reconstruction of the coil geometry variations is discussed in terms of continuous modes of deformation as well as single block displacements

Design and validation of a hardware-in-the-loop test bench for evaluating the performance of an active mass damper

The purpose of this study is to propose an innovative solution for evaluating the performance of a full-scale Active Mass Damper (AMD). The AMD adopted is a custom hydraulic actuator, developed for active control of existing buildings against earthquakes. For vibration control, a sky-hook algorithm was implemented. Its characteristics ensure good robustness, which is fundamental in structural engineering since buildings are subjected to significant variation in dynamic properties in presence of damage or ambient conditions. A Hardware-In-the-Loop (HIL) test bench was specifically designed to simulate the actual working condition of the anti-seismic system. The HIL setup consists of a shaking table moved by a hydraulic actuator in accordance with the roof's displacement, evaluated using a structural numerical model of the building to which the AMD is fixed. The presence of two distinct active systems (HIL and AMD) could generate control issues; therefore, a Triple Variable Control logic was introduced to reduce the interaction delay. The effectiveness of the proposed AMD is validated comparing the roof's displacement in an uncontrolled structure with that in a controlled one. Also, the robustness of the control algorithm was verified using a non-linear structural model and applying seismic excitation at different intensities

DESIGN AND ANALYSIS OF AN INNOVATIVE CUBESAT THERMAL CONTROL SYSTEM FOR BIOLOGICAL EXPERIMENT IN LUNAR ENVIRONMENT

After about 50 years since the Apollo missions, Space Agencies are planning new manned missions beyond LEO, aiming to full functional Lunar and Martian outposts. Leaving the protection of Earth’s magnetic field, human body will be exposed by a huge amount of harmful radiations coming from both solar wind and cosmic rays, which represent a risk for the astronauts. In order to prepare for future manned exploration missions, many biological experiments have been conducted inside and outside the International Space Station (ISS). From these experiments, engineers and scientists gained knowledge about biological degradation after a long period of exposure to space radiations. Similar experiments were also carried out in small free-flyers. For example, the O/OREOS mission is built with a 3U CubeSat that is evaluating how microorganisms can survive and can adapt to the harsh orbit environment. Small platforms, such as CubeSats, are gaining interest for many applications including science experiments. Biological payloads require very stable environmental conditions, implying that environment requirements are very stringent and that existing passive thermal control systems may not be sufficient to support these class of experiments. The goal of this paper is to describe and discuss the design of an active environmental control system suitable for supporting biological payloads hosted onboard nanosatellites. In particular, we focused the attention on the case of a payload constituted by a bacterial culture that needs oxygen supply for growing up. The rate of growth and vitality are measured through bacteria metabolic parameters. The reference mission is built with a 6U CubeSat in Lunar Polar Orbit, with the main scientific objective of measuring the effect of the lunar radiation environment on a culture of “Bacterium Deinococcus Radiodurans”. This kind of bacteria exhibits significant resistance to ionising radiation and the survival temperature range is 30°C ± 10°C. The thermal control system (TCS) is constituted by Stirling cryocooler, Peltier cells and heaters. The aforementioned pieces of equipment operate on the oxygen tank and test chamber in order to control temperature of the oxygen necessary for the growth of the bacteria. To verify the temperature requirements, two kinds of analysis are performed: radiative analysis, to have information about the heat fluxes from space environment; and lastly, a thermo-fluid dynamics analysis, to gather data about temperature in the test chamber. As result, it is possible to confirm that, with the chosen TCS, the temperature requirement is verified during the mission

Design and development of a reduced form-factor high accuracy three-axis teslameter

Acknowledgments: The authors would like to thank Reuben Debono for his useful guidance and help in the PCB assembly of the instruments at the Electronic Systems Lab at the Faculty of Engineering at University of Malta. The authors would like to thank R. Ganter, project leader of the Athos undulator beamline and H-H. Braun, SwissFEL machine director, for their constant support throughout the entire project. The authors would like to thank Sasa Spasic and his team at Sentronis facilities for their fruitful discussions and their guidance during testing.A novel three-axis teslameter and other similar machines have been designed and developed for SwissFEL at the Paul Scherrer Institute (PSI). The developed instrument will be used for high fidelity characterisation and optimisation of the undulators for the ATHOS soft X-ray beamline. The teslameter incorporates analogue signal conditioning for the three-axes interface to a SENIS Hall probe, an interface to a Heidenhain linear absolute encoder and an on-board high-resolution 24-bit analogue-to-digital conversion. This is in contrast to the old instrumentation setup used, which only comprises the analogue circuitry with digitization being done externally to the instrument. The new instrument fits in a volumetric space of 150 mm × 50 mm × 45 mm, being very compact in size and also compatible with the in-vacuum undulators. This paper describes the design and the development of the different components of the teslameter. Performance results are presented that demonstrate offset fluctuation and drift (0.1–10 Hz) with a standard deviation of 0.78 µT and a broadband noise (10–500 Hz) of 2.05 µT with an acquisition frequency of 2 kHz.peer-reviewe

Fast and efficient critical state modelling of field-cooled bulk high-temperature superconductors using a backward computation method

Abstract: A backward computation method has been developed to accelerate modelling of the critical state magnetization current in a staggered-array bulk high-temperature superconducting (HTS) undulator. The key concept is as follows: (i) a large magnetization current is first generated on the surface of the HTS bulks after rapid field-cooling (FC) magnetization; (ii) the magnetization current then relaxes inwards step-by-step obeying the critical state model; (iii) after tens of backward iterations the magnetization current reaches a steady state. The simulation results show excellent agreement with the H -formulation method for both the electromagnetic and electromagnetic-mechanical coupled analyses, but with significantly faster computation speed. The simulation results using the backward computation method are further validated by the recent experimental results of a five-period Gd–Ba–Cu–O (GdBCO) bulk undulator. Solving the finite element analysis (FEA) model with 1.8 million degrees of freedom (DOFs), the backward computation method takes less than 1.4 h, an order of magnitude or higher faster than other state-of-the-art numerical methods. Finally, the models are used to investigate the influence of the mechanical stress on the distribution of the critical state magnetization current and the undulator field along the central axis

RooHammerModel: interfacing the HAMMER software tool with the HistFactory package

Recent $B$-physics results have sparkled great interest in the search for beyond-the-Standard-Model (BSM) physics in $b\to c\ell \bar{\nu}$ transitions. The need to analyse in a consistent manner big datasets for these searches, using high-statistics Monte-Carlo (MC) samples, led to the development of HAMMER, a software tool which enables to perform a fast morphing of MC-derived templates to include BSM effects and/or alternative parameterisations of long-distance effects, avoiding the need to re-generate simulated samples. This note describes the development of RooHammerModel, an interface between this tool and the commonly-used data-fitting framework HistFactory. The code is written in C++ and admits an alternative usage in standalone RooFit analyses. In this document, the structure and functionality of the user interface are explained. Information of a public repository where it can be accessed is provided, as well as validation and performance studies of the interface. The methods developed in the construction of RooHammerModel can provide specific information for alternative future attempts to interface HAMMER with other data-fitting frameworks