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Titolo:
MODULAR MIDDLE-SCALE SQUID MAGNETOMETER SYSTEM FOR NEUROMAGNETIC RESEARCH
Autore:
HIRATA Y; KURIKI S;
Indirizzi:
HOKKAIDO UNIV,ELECT SCI RES INST SAPPORO HOKKAIDO 060 JAPAN
Titolo Testata:
IEICE transactions on electronics
fascicolo: 9, volume: E79C, anno: 1996,
pagine: 1213 - 1218
SICI:
0916-8524(1996)E79C:9<1213:MMSMSF>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
POSITIVE FEEDBACK; DC-SQUIDS; ELECTRONICS;
Keywords:
SQUID; FIELD NOISE; MAGNETOMETER; MAGNETOENCEPHALOGRAPHY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
18
Recensione:
Indirizzi per estratti:
Citazione:
Y. Hirata e S. Kuriki, "MODULAR MIDDLE-SCALE SQUID MAGNETOMETER SYSTEM FOR NEUROMAGNETIC RESEARCH", IEICE transactions on electronics, E79C(9), 1996, pp. 1213-1218

Abstract

A new 19-channel SQUID magnetometer system has been developed for research use in order to measure the neuromagnetic fields originating from cortices of the human brain. The system consists of Nb/Al-oxide/Nb SQUID sensors with 2nd-order gradiometers, tank circuits, readout electronics, a liquid helium dewar. a gantry. and a prefabricated shielded room. The gradiometers cover a circular area of 15 cm radius. We used fine stainless steel leads for electric connection between the sensorsand room-temperature electronics with low thermal conduction in a lowhelium consumption dewar. The system could Function for 6 days with aone-time supply of about 25 L of liquid helium. The system can be thermally cycled for repeated measurements, with an intervening nonusage period at room temperature. The noise characteristics, for both the time and frequency domains,:of all channels were measured. From an analysis of the voltage output at the phase-sensitive detector, the flux-origin noise which is generated by external sources was dominant in the white noise frequency. The power spectra of the noise field were below10 fT/Hz(1/2) at 10-100 Hz and below 18 fT/Hz(1/2) at 1-10 Hz. Some other peaks of power line frequencies such as 50 Hz and 150 Hz were observed at several channels. Sound-evoked magnetic fields were measured from the temporal area of the head upon application of lone bursts. The evoked fields were recorded with the amplitude of about 250 fT(pp). The isofield contours of the peak response showed that the measure ment area is large enough to estimate current dipoles. It is confirmed that the system has the ability to measure magnetic fields from the human brain.

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Documento generato il 06/04/20 alle ore 08:41:51