Editing Magnetoencephalography (section)

=== Magnetically shielded room (MSR) ===
A magnetically shielded room (MSR) model consists of three nested main layers. Each of these layers is made of a pure aluminium layer plus a high-permeability [[Ferromagnetism|ferromagnetic]] layer, similar in composition to molybdenum [[permalloy]]. The ferromagnetic layer is supplied as 1&nbsp;mm sheets, while the innermost layer is composed of four sheets in close contact, and the outer two layers are composed of three sheets each. Magnetic continuity is maintained by overlay strips. Insulating washers are used in the screw assemblies to ensure that each main layer is electrically isolated. This helps eliminate [[radio frequency]] radiation, which would degrade SQUID performance. Electrical continuity of the aluminium is also maintained by aluminium overlay strips to ensure [[alternating current|AC]] [[eddy current]] shielding, which is important at frequencies greater than 1&nbsp;Hz. The junctions of the inner layer are often electroplated with silver or gold to improve conductivity of the aluminium layers.<ref>{{cite journal | vauthors = Cohen D, Schläpfer U, Ahlfors S, Hämäläinen M, Halgren E | title = New Six-Layer Magnetically-Shielded Room for MEG | journal = Proceedings of the 13th International Conference on Biomagnetism | date = August 2002 | volume = 10 | pages = 919–921 | location = Jena, Germany | publisher = VDE Verlag | s2cid = 27016664 | url = https://pdfs.semanticscholar.org/92c5/d54611a8c35f262f82bd81b1c6223d71d29f.pdf | archive-url = https://web.archive.org/web/20200803165556/https://pdfs.semanticscholar.org/92c5/d54611a8c35f262f82bd81b1c6223d71d29f.pdf | url-status = dead | archive-date = 2020-08-03 }}</ref>