Magnetometer utilizing SQUID pico-voltmeter and cooled normal pickup coil

✍ Scribed by Tong Qing Yang; Kenichiro Yao; Daisuke Yamasaki; Keiji Enpuku

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 222 KB
• Volume: 426-431
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2005.01.080

✦ Synopsis

Magnetometer utilizing a high-T c SQUID pico-voltometer and cooled normal pickup coil has been developed. The pickup coil was made of copper wire, and cooled to T = 77 K in order to decrease thermal noise from resistance. Total voltage noise of the SQUID pico-voltmeter with a cooled pickup coil was 124 pV/Hz 1/2 and 96 pV/Hz 1/2 at 100 Hz and 1 kHz, respectively, when resistance of the coil was 1.5 X. The magnetic field noise of the magnetometer was 130 pT/ Hz 1/2 and 10 pT/Hz 1/2 at 100 Hz and 1 kHz for the pickup coil with 4.4 mm diameter, respectively. Application of the magnetometer to non-destructive evaluation was presented. It is shown that small crack inside Cu plate can be detected with this system in unshielded environment. It was also shown that scanning of the pickup coil in unshielded environment is possible without degradation of the system performance.