Andrew Sammut

Increasingly powerful accelerator facilities, characterised by pulsed high-intensity beams with small transverse dimensions, challenge the survivability of interceptive beam diagnostic instruments due to beam-induced heating and risk of damage. This work characterises the thermal response of diagnostic wires under high-intensity irradiation using a combined experimental and numerical approach. The experimental study is performed on tungsten wires irradiated by 160 MeV H ^- pulses. Thermionic emission is exploited as a temperature-dependent observable, enabling indirect monitoring of wire heating over microsecond-scale pulse durations. A three-dimensional transient thermal model is developed to reproduce the experimental conditions. The model predicts wire temperatures exceeding 3000 K for the longest pulses. Experimental and numerical results show that thermionic currents closely follow the temperature evolution, with peaks rising exponentially with the duration of the pulse. Good agreement is observed up to intermediate pulse lengths. For longer pulses, discrepancies emerge, indicating the onset of external effects such as thermionic-induced space charge, coating loss, sublimation and wire-cross talk.

The next generation of experiments on charged lepton flavor violation demands higher muon rates. To achieve this, one of the existing target stations at the Paul Scherrer Institute's high-intensity proton accelerator, along with its two connected beamlines, will be dismantled and rebuilt as part of the High Intensity Muon Beams (HIMB) project, under the Swiss Roadmap for Research Infrastructures initiative, IMPACT. The new MuH2 and MuH3 beamlines will rely on 15 large-aperture solenoids and 5 dipoles for muon beam transport, designed to handle a large phase-space beam. Our estimates of the absorbed dose levels indicate that five transport solenoids and two dipoles must be radiation-resistant, requiring the use of mineral-insulated cables, whilst the other magnets can utilize epoxy-impregnated coils. Currently, the design of transport beamline components is based on standard resistive magnets, which suffer from high power consumption. This study aims to explore an alternative using Nb-Ti superconducting coils to reduce power consumption. The paper focuses on the design study of transport solenoids and includes a thermo-economic analysis, considering radiation exposure at three positions relative to the target.

The magnetic field optimization of RE-Ba-Cu-O (REBCO, RE = rare earth) bulk superconducting undulators is a fundamental step toward their implementation in an accelerator driven photon source, like a synchrotron or a free electron laser. In this article, we propose a sorting algorithm to reduce the undulator’s phase error based on the reconstruction of the trapped current inside the bulks of a staggered array undulator. The results obtained with a YBCO short prototype field-cooled down to 10 K in a 10 T magnetic field are reported. Finally, its performance is critically discussed in light of 2D magnetic field maps of its individual components, obtained at LN 2 after the magnetization tests. Published by the American Physical Society 2024

A new reduced form-factor three axes digital teslameter, based on the spinning current technique, has been developed. This instrument will be used to characterize the SwissFEL insertion devices at the Paul Scherrer Institute (PSI) for the ATHOS soft X-ray beamline. A detailed and standardized calibration procedure is critical to optimize the performance of this precision instrument. This paper presents the measurement techniques used for the corrective improvements implemented through non-linearity, temperature offset, temperature sensitivity compensation of the Hall probe and electronics temperature compensation. A detailed quantitative analysis of the reduction in errors on the application of each step of the calibration is presented. The percentage peak error reduction attained through calibration of the instrument for reference fields in the range of ±2 T is registered to drop from 1.94% down to 0.02%.

In the framework of the SwissFEL project at the Paul Scherrer Institute (PSI), a Hall probe bench is being developed for the high-precision magnetic characterization of the insertion devices for the ATHOS soft X-ray beamline. For this purpose, a novel three-axis teslameter has been developed, which will be placed between the undulator and its outer shell in a very limited volumetric space of 150 × 50 × 45 mm. Together with a SENIS^® 3-axis Hall probe at the center of the cross sectional area of the undulator, the setup will traverse along the undulator length on a specifically designed rig with minimal vibrations. This teslameter has all the analog signal conditioning circuitry for the Hall probe and also has on board 24-bit digitization. The instrument also handles an interface to a linear absolute encoder. The old instrumentation used only had analog signal conditioning circuitry whilst digitization was done off board. The new instrument also provides a very accurate magnetic field map in the µT range with simultaneous readings from the position encoder at an accuracy of ±3 µm. In this paper, a series of tests are described, which were performed at PSI in order to establish the measuring precision and repeatability of the instrument.

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.

Most modern outdoor tracking systems utilize GPS technology. However, typical pedestrian environments tend to distort and block satellite signals, thereby making GPS communication systems unreliable. This is particularly true for indoor environments. An alternative pedestrian dead reckoning system based solely on inertial sensors is presented. Noisy acceleration signals result in a heavy velocity drift. This study proposes static-period and dynamic-period compensation methods that would allow for accurate 2-D positioning to be estimated. Data fitting techniques are used to reset velocity drift error after every step, thereby preventing accumulation of errors, as well as to compensate for the errors incurred during the step itself. Results show that the combined system is able to track rectilinear motion under normal walking conditions with an average accuracy of 1.4%, while various lengths of non-linear 2-D paths travelled by different users with varying gaits, paces and directions were successfully tracked with a maximum error of 5%.

Runway conflicts pose a significant threat to continued safety in commercial aviation. In recent years, stakeholders have initiated a number of programmes dealing with the issue of runway incursions, with the majority adopting traditional advisory alerting techniques. In contrast, this work proposes the use of directive cockpit alerting, which provides both an alert of the conflict as well as guidance on which manoeuvre to conduct to clear the conflict. This article reports the findings of simulator trials that have been conducted to assess the effectiveness and acceptability of a directive alerting strategy within the context of runway incursions. Statistical analysis performed on the quantitative measures taken from the evaluations have shown that the directive mode of alerting leads to a higher probability of the crew performing the correct action when faced with an alert. This, together with overall participant acceptance of the directive alerting concept, is a strong indicator that the technique has the potential of providing a complete solution to the problem of runway incursions.