Optimising and Extending A Single-Particle Tracking Library For High Parallel Performance

SixTrackLib is a library for performing tracking simulations on highly parallel systems such as shared memory multi-core processors or graphical processing units (GPUs). Its single-particle approach fits very well to parallel implementations with reasonable base-line performance, making such a library an interesting building block for various use cases, including simulations covering collective effects. We describe the optimisations applied to SixTrackLib to improve its performance on its main target platforms and the associated performance gain. Furthermore we outline the technical interfaces and extensions implemented to allow its use in a wider range of applications and studies

Using Airborne Measurements to Model the Satellite-to-Aircraft Channel Model at L-Band

Radio wave propagation from a satellite based emitter to an airborne located receiver is of interest for applications like passenger internet access during a flight, air traffic management or positioning by global navigation satellite systems (GNSSs). Especially for the last two applications that are related to safety-of-life functionality, accurate channel models for software based system testing are essential. Current state-of-the art channel models for the satellite-to-aircraft case lack of accuracy in terms of modeling all propagation impairments. In this contribution, we describe an airborne experiment using Global Positioning System (GPS) satellite emitted signals to characterize the wave propagation channel from a satellite to an airborne platform. First results on ground reflected multipath are provided

Airborne Measurements Enhancing the Satellite-to-Aircraft Channel Model in L-Band

This paper reports the experimental design and implementation in a realistic environment of an airborne measurement set-up aiming at improving the quality and reliability of an aeronautical satellite transmission channel model in L-band. An improved satellite-to-aircraft channel model will allow more accurate predictions of the reception situation by considering all propagation related effects. This accuracy is important when developing and testing novel systems for critical safety-of-life application. The improvement of the channel model necessitates to assess, among other influences, the effects of the airborne platform on the electromagnetic pattern of the antennae for both fixed- and rotary-winged aircraft and the quantification of the ground-reflection characteristics in the frequency-band of interest. The herein presented activities are rounding out an extensive experimental campaign and build the continuation of the ground-based measurements outlined in a previous paper

Ground Reflection for Low Elevations at L- and K-Band

Obviously, only satellite-based communication systems can supply aircraft with reliable communications in remote airspace. To cope with the rising requirements on data rates, carrier frequencies above 18GHz are considered nowadays. Generally, at these higher frequencies, the effect of ground originated multipath will be less severe due to the spatial discrimination of employed directional antennas. Nevertheless, for satellites seen at low elevation angles, ground originated multipath will superpose the direct signal. Therefore, investigations into the ground reflected signals at L- and K-band are performed and described in this paper. Measurements were performed for water, meadow, ice, dry and irrigated concrete surfaces. Finally, we provide the right hand circular polarized (RHCP) Fresnel reflection coefficient at L-band while for K-band, we provide the RHCP and left hand circular polarized (LHCP) Fresnel reflection coefficient

Wide-Band Characterization of Antennae Plus Aircraft Platform Patterns in L- and Ka-Band

The aim of the presented activities is to improve the quality and reliability of aircraft bound wide-band satellite transmissions for current and up-coming communication- and air-traffic management applications by means of developing simulation tools based upon an improved model for the transmission channel. Among other influences, the effects of the airborne platform itself onto the electromagnetical pattern of airborne antennae for both fixed- and rotary-wing aircraft have to be assessed and quantified towards the end of inclusion into an updated channel model. Within this paper, the motivation, design and the experimental execution of a series of campaigns involving commercially available, off-the-shelf (COTS) antennae and four different aircraft (two fixed wing planes and two helicopters) are outlined. Moreover, the experimental execution is described and first results from these measurements are presented

New optics design of the Cherenkov threshold detectors at CERN

The performance of the Cherenkov threshold detectors (XCET) used in the secondary beam areas (SBA) at CERN is limited by their built-in optics. This study showcases an improved design using compound parabolic concentrators (CPCs) to reduce size and cost of the optics while optimizing the light collection efficiency. The detector was simulated with Geant4 over its full experimental range in terms of pressure, beam momentum, and particle type. The efficiency of the current design was found to be limited by the geometry of the parabolic mirror. The optimized CPC designs resulted in a size reduction of up to 54% and improved photon collection up to 67% compared to the original design when using CO2 as radiator gas and 276% when using R-218. These results highlight the advantages of using CPC and Monte Carlo simulations in the development of Cherenkov threshold detectors and may be useful for further improvements in the next generation of the XCET

SixTrack project: Status, runtime environment, and new developments

SixTrack is a single-particle tracking code for high-energy circular accelerators routinely used at CERN for the Large Hadron Collider (LHC), its luminosity upgrade (HL-LHC), the Future Circular Collider (FCC), and the Super Proton Synchrotron (SPS) simulations. The code is based on a 6D symplectic tracking engine, which is optimised for long-term tracking simulations and delivers fully reproducible results on several platforms. It also includes multiple scattering engines for beam-matter interaction studies, as well as facilities to run integrated simulations with FLUKA and GEANT4. These features differentiate SixTrack from general-purpose, optics-design software like MAD-X. The code recently underwent a major restructuring to merge advanced features into a single branch, such as multiple ion species, interface with external codes, and high-performance input/output (XRootD, HDF5). This restructuring also removed a large number of build flags, instead enabling/disabling the functionality at run-time. In the process, the code was moved from Fortran 77 to Fortran 2018 standard, also allowing and achieving a better modularization. Physics models (beam-beam effects, RF-multipoles, current carrying wires, solenoid, and electron lenses) and methods (symplecticity check) have also been reviewed and refined to offer more accurate results. The SixDesk runtime environment allows the user to manage the large batches of simulations required for accurate predictions of the dynamic aperture. SixDesk supports CERN LSF and HTCondor batch systems, as well as the BOINC infrastructure in the framework of the LHC@Home volunteering computing project. SixTrackLib is a new library aimed at providing a portable and flexible tracking engine for single- and multi-particle problems using the models and formalism of SixTrack. The tracking routines are implemented in a parametrized C code that is specialised to run vectorized in CPUs and GPUs, by using SIMD intrinsics, OpenCL 1.2, and CUDA technologies. This contribution presents the status of the code and an outlook on future developments of SixTrack, SixDesk, and SixTrackLib

SixTrack Version 5: Status and New Developments

SixTrack Version 5 is a major SixTrack release that introduces new features, with improved integration of the existing ones, and extensive code restructuring. New features include dynamic-memory management, scattering-routine integration, a new initial-condition module, and reviewed post-processing methods. Existing features like on-line aperture checking and Fluka-coupling are now enabled by default. Extensive performance regression tests have been developed and deployed as part of the new-release generation. The new features of the tracking environment developed for the massive numerical simulations will be discussed as well