NMR DETECTION AT 8.9 mT WITH A GMR BASED SENSOR COUPLED TO A SUPERCONDUCTING Nb FLUX TRANSFORMER

Abstract : —This study presents NMR signal detection by means of a superconducting channel consisting of a Nb surface detection coil inductively coupled to a YBCO mixed sensor. The NMR system operates at a low-field (8.9 mT) in a magnetically shielded room suitable for magnetoencephalographic (MEG) recordings. The main field is generated by a compact solenoid and the geometry of the pickup coil has been optimized to provide high spatial sensitivity * Corresponding author: Raffaele Sinibaldi (r.sinibaldi@unich.it). 390 Sinibaldi et al. in the NMR field of view. The Nb detection coil is coupled to the mixed sensor through a Nb input coil. The mixed sensor consists of a superconducting YBCO loop with 2-µm constriction above which two Giant MagnetoResistance sensors are placed in a half-bridge configuration to detect changes of the bridge voltage as a function of the flux through the YBCO loop. The sensitivity of the receiving channel is calibrated experimentally. The measured spatial sensitivity is in agreement with the simulations and is ∼10 times better than that of the stand-alone mixed sensor. A NMR echo at 375 kHz shows a SNR only a factor 4 smaller than a tuned room temperature coil tightly wound around the sample, with a noise level which is a factor 3 better than for the volume coil. Our results suggest that mixed sensors are suitable for the integration of low-field MRI and MEG in a hybrid apparatus, where MEG and MRI would be recorded by SQUIDs and mixed sensors, respectively.
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Progress In Electromagnetics Research, EMW Publishing, 2013, 142, pp.389 - 408. 〈10.2528/PIER13070404〉
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Dernière modification le : jeudi 11 janvier 2018 - 06:27:30

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Raffaele Sinibaldi, Cinzia De Luca, Jaakko O. Nieminen, Angelo Galante, Vittorio Pizzella, et al.. NMR DETECTION AT 8.9 mT WITH A GMR BASED SENSOR COUPLED TO A SUPERCONDUCTING Nb FLUX TRANSFORMER. Progress In Electromagnetics Research, EMW Publishing, 2013, 142, pp.389 - 408. 〈10.2528/PIER13070404〉. 〈cea-01481107〉

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