Magnetic Noise in a Magnetically-Shielded Room due to Mechanical Vibration

Abstract

Event Abstract Back to Event Magnetic Noise in a Magnetically-Shielded Room due to Mechanical Vibration Keita Yamazaki1*, Takayuki Abe1, Norio FujiMaki2, Tsutomu Murata2 and Koichiro Kobayashi3 1 Takenaka Corporation, Japan 2 National Institute of Information and Communications Technology, Japan 3 Iwate University, Japan An Active Microtremor Isolation (ACMI) system is used as the basement of a Magnetically Shielded Room (MSR) to reduce vibration. We measured vibrations of the MSR and the magnetic noises (MNs) inside the MSR to know the relationship between them under the normal condition and the condition in which artificial vibration was applied to the concrete slab (CS). Since the accelerations of ceiling outside the MSR (Arx, Arz) were reduced by the ACMI at frequencies from 1 to 100 Hz, they were considered to be caused by mechanical vibration via floor. However, the velocity of the wall (Lwx) and ceiling (Lrz), and the MNs inside the MSR were reduced by the ACMI at frequencies higher than 10 Hz, but not less than 10 Hz. Since the velocities were measured by the vibrometer placed inside the MSR, this suggests that the mechanical vibration caused the MSR to tremble with deformation at frequencies higher than 10 Hz, but without deformation at frequencies lower than 10 Hz; the former one produced MNs. The coherence functions (CFs) at frequencies from 10 to 20 Hz were high (peaking more than 0.9) between Lwx / Lrz, and MNs for ACMI-OFF. Among a few peaks of CFs, a peak at 16.7 Hz is considered to reflect mechanical resonance properties (MRPs) of the MSR, which agrees with that analyzed by a finite element analysis of structure composed by flames and shield panels When controlled footsteps were applied on the CS, MNs and the accelerations of ceiling outside the MSR differed at frequencies higher than 10 Hz, where the peaks at 45 and 52 Hz are considered to reflect the higher mode of MRP of the MSR. The CFs at frequencies from 10 to 20 Hz, and 30 to 70 Hz, were high (peaking more than 0.9) between Arx and MNs for ACMI-OFF. In summary, the present results show that MNs due to vibrations depend on fundamental mode (10-20 Hz) of MRP under the normal condition, while both on fundamental and higher modes (10-20 Hz, and 30-70 Hz) of MRP when artificial vibration was applied to the CS. This work was supported by the Japan Society for the Promotion of Science for Grant-in-Aid for Exploratory Research 20651043. Conference: Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010. Presentation Type: Poster Presentation Topic: Instrumentation and Multi-modal Integrations: MEG, Low-field MRI,EEG, fMRI,TMS,NIRS Citation: Yamazaki K, Abe T, FujiMaki N, Murata T and Kobayashi K (2010). Magnetic Noise in a Magnetically-Shielded Room due to Mechanical Vibration. Front. Neurosci. Conference Abstract: Biomag 2010 - 17th International Conference on Biomagnetism . doi: 10.3389/conf.fnins.2010.06.00423 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 09 Apr 2010; Published Online: 09 Apr 2010. * Correspondence: Keita Yamazaki, Takenaka Corporation, Inzai, Japan, keita-y@sam.hi-ho.ne.jp Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Keita Yamazaki Takayuki Abe Norio FujiMaki Tsutomu Murata Koichiro Kobayashi Google Keita Yamazaki Takayuki Abe Norio FujiMaki Tsutomu Murata Koichiro Kobayashi Google Scholar Keita Yamazaki Takayuki Abe Norio FujiMaki Tsutomu Murata Koichiro Kobayashi PubMed Keita Yamazaki Takayuki Abe Norio FujiMaki Tsutomu Murata Koichiro Kobayashi Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.