Metrological Characterization of Nuclear Magnetic Resonance Markers for Real-Time Field Control of the CERN ELENA Ring Dipoles

Field markers in particle accelerators are used to provide a digital trigger when the magnetic field reaches a preset threshold. This paper describes the results of a test campaign performed on the extra low energy antiproton decelerator's main bending dipoles at the European Organization for Nuclear Research (CERN) investigating the behavior of nuclear magnetic resonance (NMR) markers in ramping fields. Following the conclusions of an off-line study using a spare dipole, a series of tests performed on the reference magnet powered in series with the ring showed an NMR signal with a reproducibility better than 9 $\mu$T at field levels lower than 47 mT, using slow ramp rates. This is promising for the real-time field control of the decelerator. For a high-field marker using high ramp rates, the reproducibility of the signal was found to be better than 3 $\mu$T

A single-chip integrated transceiver for high field NMR magnetometry

We present the design and performance of a broad-band single-chip integrated transceiver specifically conceived for nuclear magnetic resonance magnetometry. The single-chip transceiver is realized using a standard silicon complementary metal-oxide-semiconductor integrated circuit technology. A radio-frequency (RF) transmit amplifier, a transmit/receive switch, a low noise RF receive amplifier, a quadrature (IQ)-mixer, and two intermediate frequency amplifiers are integrated on a single silicon chip of 1.8 mm(2). The advantages and problematic aspects with respect to conventional discrete electronic approaches are discussed. We show the results of magnetic field measurements performed at 1.4 and 7.05 T, using solid and liquid samples having volumes from 40 mu l down to 100 pl. Particular attention is devoted to the comparison of the experimentally measured magnetic field standard deviation with respect to the Cramer-Rao lower bound value. With a sample of distilled water (T-1 congruent to T-2 congruent to 3 s, T-2(*) congruent to 20 ms) having a volume of 40 mu l, a standard deviation of 2.5 nT at 7.05 T (i.e., 0.5 ppb) in 1 s of averaging time is achieved, with a projected Cramer-Rao lower bond of 8 pT (i.e., 1.1 ppt). Published under license by AIP Publishing

First field trials with a portable CIS processor for the Ineraid multichannel cochlear implant

The continuous interleaved sampling (CIS) strategy is a promising sound processing strategy for multichannel cochlear implants which provides immediate improvements in speech recognition when tested on Ineraid users: patients with only a few hours of experience (in laboratory testing) with the CIS strategy score better than with the Ineraid prosthesis they used since they, were implanted. The goal of this study was to evaluate the benefits that can be gained by the use of the new strategy in every day life. Two patients, implanted with the Ineraid multichannel cochlear implant, were equipped with a portable numerical processor programmed to implement a high rate CIS strategy. Their speech recognition was evaluated periodically with consonant and vowel identification tests for more than 6 months of use. Tests were also made with the Ineraid processor during the same experimental sessions and patients were regularly interviewed about their experience. Performance with the portable CIS processor was superior or equal to that obtained previously in the laboratory with the same strategy. Both patients achieved the best scores in 6 years of cochlear implant use. Qualitative reports from the patients suggest that the CIS strategy can improve "hearing" performance of cochlear implant users in many important situations of every day life. Altogether, these results hold great promises for all users of the Ineraid multichannel cochlear implant

Perception du langage des utilisateurs d'implants cochléaires récents

Une grande partie des implants cochléaires de dernière génération utilisent des stratégies du codage des sons, dites CIS, dont les particularités essentielles sont de stimuler toujours les mêmes électrodes implantées, les unes après les autres, à une vitesse très rapide. Nous décrivons ici la perception du langage de deux groupes d'adultes utilisant ce type de codage des sons sur deux systèmes d'implants cochléaires très différents : un système développé il y a presque vingt ans mais bénéficiant d'un nouveau processeur de recherche et un système commercial très récent. Cette étude montre que tous ces patients obtiennent grâce au codage CIS une bonne perception du langage, permettant à la majorité d'entre eux de converser au téléphone