Error characterization and calibration of real-time magnetic field measurement systems

In synchrotrons at the European Organization for Nuclear Research (CERN), magnetic measurement systems known as B-trains measure the magnetic field in the main bending magnets in real-time, and transmit this signal for the control of the synchrotron’s RF accelerating cavities, magnet power converter and beam monitoring systems. This work presents an assessment of the capabilities and performance of the new FIRESTORM (Field In REal-time STreaming from Online Reference Magnets) system as part of the first phase of commissioning. A short summary of the architecture of the measurement system is provided first, followed by the definition of an error model which can be used to characterize random and systematic errors separately. We present a procedure for the metrological calibration and qualification of the B-trains, including an experimental evaluation of the different error sources for the four new systems being commissioned in the Proton Synchrotron Booster (PSB), Low Energy Ion Ring (LEIR), Proton Synchrotron (PS) and the Extra Low ENergy Antiproton (ELENA) ring. In particular, we discuss a method to calibrate systematic gain and offset errors based on the RF cavity frequency offset needed to center the beam on its theoretical orbit

A hall plate based instrument to measure the snapback in the Large Hadron Collider superconducting dipole magnets

The decay and snapback of the magnetic field multipoles in superconducting particle accelerators like the Large Hadron Collider (LHC) could result in a significant particle beam loss unless adequately compensated. Whilst standard instrumentation used to measure the field quality of the superconducting magnets is good enough to measure the harmonic decay, it is not fast enough to measure the snapback. Therefore, a state of the art instrument was recently developed at CERN to measure the most important harmonics with a high measurement frequency and hence improve the understanding of the snapback phenomenon. In this paper we describe the instrument's principle of operation, its mechanical arrangement, its compensation system and its digital acquisition system. We also compare the performance of two different techniques implemented to achieve the necessary measurement resolution of 6 orders of magnitude lower than the main superimposed dipole field.peer-reviewe

Electron paramagnetic resonance magnetic field sensors for particle accelerators

We report on four electron paramagnetic resonance sensors for dynamic magnetic field measurements at 36 mT, 100 mT, 360 mT, and 710 mT. The sensors are based on grounded co-planar microwave resonators operating at about 1 GHz and 3 GHz, realized using printed circuit board technology, and on single-chip integrated microwave oscillators operating at about 10 GHz and 20 GHz, realized using complementary metal-oxide-semiconductor technology. The sensors are designed to mark precisely the moment when a time-dependent magnetic field attains a specific value. The trigger from the sensor can be used to preset the output of real-time magnetic field measurement systems, called "B-trains," which are in operation at several large synchrotron installations, including five of the CERN's particle accelerators. We discuss in detail the performance achieved, in particular, the magnetic field resolution that is in the range of 0.1 nT/Hz(1/2)-6 nT/Hz(1/2). The effects of material anisotropy and temperature are also discussed. Finally, we present a detailed characterization of the sensors with field ramps as fast as 5 T/s and field gradients as strong as 12 T/m

Development of a Real-Time Magnetic Field Measurement System for Synchrotron Control

The precise knowledge of the magnetic field produced by dipole magnets is critical to the operation of a synchrotron. Real-time measurement systems may be required, especially in the case of iron-dominated electromagnets with strong non-linear effects, to acquire the magnetic field and feed it back to various users. This work concerns the design and implementation of a new measurement system of this kind currently being deployed throughout the European Organization for Nuclear Research (CERN) accelerator complex. We first discuss the measurement principle, the general system architecture and the technology employed, focusing in particular on the most critical and specialized components developed, that is, the field marker trigger generator and the magnetic flux integrator. We then present the results of a detailed metrological characterization of the integrator, including the aspects of drift estimation and correction, as well as the absolute gain calibration and frequency response. We finally discuss the latency of the whole acquisition chain and present an outline of future work to improve the capabilities of the system

Instruments and Methods for the Magnetic Measurement of the Super-FRS Magnets

The Super-FRS is a new fragment separator to be built as part of the Facility for Antiproton and Ion Research (FAIR) [\ref{fair_{w}eb}] at Darmstadt. The acceptance tests and magnetic measurements of the superferric separation dipoles and multiplets (containing quadrupole and higher-order magnets) will be performed at CERN in collaboration with GSI/FAIR [\ref{abstract_{f}acility}]. This paper presents the methods and challenges of the magnetic field measurements, and the required instruments for measuring the transfer function, field quality, and magnetic axis. A prototype for each system has been produced in order to validate the measurement methods, the instruments, and the mechanical integration. In this paper will present the design and production of the prototypes, the design of the instruments for the series measurements, and the results of the metrological characterization

Metabolic diversity among main microorganisms inside an arsenic-rich ecosystem revealed by meta-and proteo-genomics

International audienceBy their metabolic activities, microorganisms have a crucial role in the biogeochemical cycles of elements. The complete understanding of these processes requires, however, the deciphering of both the structure and the function, including synecologic interactions, of microbial communities. Using a metagenomic approach, we demonstrated here that an acid mine drainage highly contaminated with arsenic is dominated by seven bacterial strains whose genomes were reconstructed. Five of them represent yet uncultivated bacteria and include two strains belonging to a novel bacterial phylum present in some similar ecosystems, and which was named 'Candidatus Fodinabacter communificans.' Metaproteomic data unravelled several microbial capabilities expressed in situ, such as iron, sulfur and arsenic oxidation that are key mechanisms in biomineralization, or organic nutrient, amino acid and vitamin metabolism involved in synthrophic associations. A statistical analysis of genomic and proteomic data and reverse transcriptase-PCR experiments allowed us to build an integrated model of the metabolic interactions that may be of prime importance in the natural attenuation of such anthropized ecosystems