A Demonstration Experiment for the Main Field Tracking and the Sextupole and Decapole Compensation in the LHC Main Magnets

A dedicated measurement campaign was set up to test the FiDeL concept and its LSA implementation. The test was performed by demonstrating the tracking of B1 and B2 for two LHC main dipoles and one LHC main quadrupole. It also included the compensation of the b3 and b5 harmonics in the dipole magnets using the sextupole and decapole corrector magnets. In this report we present the techniques developed to power the magnets for these tests during the current ramps; the instrumentation and data acquisition setup used to perform the tracking experiments; the calibration procedure and data corrections employed; and finally the main results obtained

Lightning mapping sensor study

A technology assessment to determine how a world-wide, continuous measurement of lightning could be achieved from a geostationary platform is provided. Various approaches to the detector sensors are presented. It was first determined that any existing detector chips would require some degree of modification in order to meet the lightning mapper sensor requirements. The elements of the system were then analyzed, categorized, and graded for study emphasis. The recommended approach for the lightning mapper sensor is to develop a monolithic array in which each detector cell has circuitry that implements a two-step photon-collecting method for a very high dynamic range with good measurement accuracy. The efficiency of the array is compatible with the use of a conventional refractive optics design having an aperture in the neighborhood of 7 to 10 cm

A pulsed Sagnac source of narrowband polarization-entangled photons

We demonstrate pulsed operation of a bidirectionally pumped polarization Sagnac interferometric down-conversion source and its generation of narrowband, high-visibility polarization-entangled photons. Driven by a narrowband, mode-locked pump at 390.35 nm, the phase-stable Sagnac source with a type-II phase-matched periodically poled KTiOPO$_4$ crystal is capable of producing 0.01 entangled pair per pulse in a 0.15-nm bandwidth centered at 780.7 nm with 1 mW of average pump power at a repetition rate of 31.1 MHz. We have achieved a mean photon-pair generation rate of as high as 0.7 pair per pulse, at which multi-pair events dominate and significantly reduce the two-photon quantum-interference visibility. For low generation probability $\alpha$, the reduced visibility $V=1-\alpha$ is independent of the throughput efficiency and of the polarization analysis basis, which can be utilized to yield an accurate estimate of the generation rate $\alpha$. At low $\alpha$ we have characterized the source entanglement quality in three different ways: average quantum-interference visibility of 99%, the Clauser-Horne-Shimony-Holt $S$ parameter of $2.739 \pm 0.119$, and quantum state tomography with 98.85% singlet-state fidelity. The narrowband pulsed Sagnac source of entangled photons is suitable for use in quantum information processing applications such as free-space quantum key distribution.Comment: 10 pages, 6 figures, accepted for publication in Phys. Rev.

Pierre Auger Observatory status and results

The Pierre Auger Observatory, a hybrid detector for the study of ultra-high energy cosmic rays (UHECRs), is now approaching completion. After describing Auger present status and performance, with an emphasis on the advantages provided by the combination of two different detection techniques, this contribution presents a brief panorama of the first scientific results achieved and of their impact on our knowledge of the UHECRs' origin and composition.Comment: 8 pages, 4 figures (references added/corrected). Prepared for the proceedings of the 42nd Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Italy, 10-17 Mar 200

Portable Ultrasound Imaging

This PhD project investigates hardware strategies and imaging methods for hand-held ultrasound systems. The overall idea is to use a wireless ultrasound probe linked to general-purpose mobile devices for the processing and visualization. The approach has the potential to reduce the upfront costs of the ultrasound system and, consequently, to allow for a wide-scale utilization of diagnostic ultrasound in any medical specialties and out of the radiology department. The first part of the contribution deals with the study of hardware solutions for the reduction of the system complexity. Analog and digital beamforming strategies are simulated from a system-level perspective. The quality of the B-mode image is evaluated and the minimum specifications are derived for the design of a portable probe with integrated electronics in-handle. The system is based on a synthetic aperture sequential beamforming approach that allows to significantly reduce the data rate between the probe and processing unit. The second part investigates the feasibility of vector flow imaging in a hand-held ultrasound system. Vector flow imaging overcomes the limitations of conventional imaging methods in terms of flow angle compensation. Furthermore, high frame rate can be obtained by using synthetic aperture focusing techniques. A method is developed combining synthetic aperture sequential beamforming and directional transverse oscillation to achieve the wireless transmission of the data along with a relatively inexpensive 2-D velocity estimation. The performance of the method is thoroughly assessed through simulations and measurements, and in vivo investigations are carried out to show its potential in presence of complex flow dynamics. A sufficient frame rate is achieved to allow for the visualization of vortices in the carotid bifurcation. Furthermore, the method is implemented on a commercially available tablet to evaluate the real-time processing performance in the built-in GPU with concurrent wireless transmission of the data. Based on the demonstrations in this thesis, a flexible framework can be implemented with performance that can be scaled to the needs of the user and according to the computing resources available. The integration of high-frame-rate vector flow imaging in a hand-held ultrasound scanner, in addition, has the potential to improve the operator’s workflow and opens the way to new possibilities in the clinical practice

Temporal and spatial combining for 5G mmWave small cells

This chapter proposes the combination of temporal processing through Rake combining based on direct sequence-spread spectrum (DS-SS), and multiple antenna beamforming or antenna spatial diversity as a possible physical layer access technique for fifth generation (5G) small cell base stations (SBS) operating in the millimetre wave (mmWave) frequencies. Unlike earlier works in the literature aimed at previous generation wireless, the use of the beamforming is presented as operating in the radio frequency (RF) domain, rather than the baseband domain, to minimise power expenditure as a more suitable method for 5G small cells. Some potential limitations associated with massive multiple input-multiple output (MIMO) for small cells are discussed relating to the likely limitation on available antennas and resultant beamwidth. Rather than relying, solely, on expensive and potentially power hungry massive MIMO (which in the case of a SBS for indoor use will be limited by a physically small form factor) the use of a limited number of antennas, complimented with Rake combining, or antenna diversity is given consideration for short distance indoor communications for both the SBS) and user equipment (UE). The proposal’s aim is twofold: to solve eroded path loss due to the effective antenna aperture reduction and to satisfy sensitivity to blockages and multipath dispersion in indoor, small coverage area base stations. Two candidate architectures are proposed. With higher data rates, more rigorous analysis of circuit power and its effect on energy efficiency (EE) is provided. A detailed investigation is provided into the likely design and signal processing requirements. Finally, the proposed architectures are compared to current fourth generation long term evolution (LTE) MIMO technologies for their anticipated power consumption and EE

The PiSpec: A Low-Cost, 3D-Printed Spectrometer for Measuring Volcanic SO2 Emission Rates

Spectroscopy has been used to quantify volcanic gas emission rates, most commonly SO2, for a number of decades. Typically, commercial spectrometers costing 1000s USD are employed for this purpose. The PiSpec is a new, custom-designed, 3D-printed spectrometer based on smartphone sensor technology. This unit has ≈1 nm spectral resolution and a spectral range in the ultraviolet of ≈280–340 nm, and is specifically configured for the remote sensing of SO2 using Differential Optical Absorption Spectroscopy (DOAS). Here we report on the first field deployment of the PiSpec on a volcano, to demonstrate the proof of concept of the device’s functionality in this application area. The study was performed on Masaya Volcano, Nicaragua, which is one of the largest emitters of SO2 on the planet, during a period of elevated activity where a lava lake was present in the crater. Both scans and traverses were performed, with resulting emission rates ranging from 3.2 to 45.6 kg s−1 across two measurement days; these values are commensurate with those reported elsewhere in the literature during this activity phase (Aiuppa et al., 2018; Stix et al., 2018). Furthermore, we tested the PiSpec’s thermal stability, finding a wavelength shift of 0.046 nm/∘C between 2.5 and 45∘C, which is very similar to that of some commercial spectrometers. Given the low build cost of these units (≈500 USD for a one-off build, with prospects for further price reduction with volume manufacture), we suggest these units hold considerable potential for volcano monitoring operations in resource limited environments