MSR for very low-field applications

The magnetically shielded room (MSR) for low-field applications is intended for experiments in ambient fields smaller than 50 nT. These include magnetic field sensor calibration, various physical experiments, simulating interplanetary/interstellar magnetic field conditions, or the monitoring of bio-magnetic signals (e.g. magnetocardiography and magnetoencephalography).

The exterior shield consists of a double layer of electrical steel (2 x 1 mm thick) and has on all faces direct current (DC) coil windings (vertical and north-south horizontal) to impart an anhysteretic remanent magnetisation (ARM). The interior shield is made of a single mu-metal layer (1 mm thick) and is equipped with active DC coils to compensate small static and dynamic residual fields (and linear field gradients) . The low-field MSR has internal dimensions of 3.81 x 3.05 x 2.15 m (L, W, H) and is oriented in an east-west direction (length). It contains no cables or installations, except those necessary for field compensation. Electricity, data cables and lighting can be brought inside using mobile devices.

1. Constructing the floor frame comes first.
1. Constructing the floor frame comes first.
2. Preparing the floor.
2. Preparing the floor. The photo shows: Aluminium foil for some RF shielding, just in case of VHF ground reflections; a copper wire winding which is part of the floor's ARM coils, and a hard foam mat for protection of the floor outer shield.
3. Now comes the installation of the floor’s outer shield: a double layer of electrical steel.
3. Now comes the installation of the floor’s outer shield: a double layer of electrical steel.
4. Fixing wires of the floor’s ARM coils before putting on the floor frame.
4. Fixing wires of the floor’s ARM coils before putting on the floor frame.
5. The floor frame has been installed, and the side frames will be mounted next. The MSR for palaeomagnetic applications can be seen in the background.
5. The floor frame has been installed, and the side frames will be mounted next. The MSR for palaeomagnetic applications can be seen in the background.
6. Wires from the ARM coils of the ceiling.
6. Wires from the ARM coils of the ceiling.
7. The wooden frame is ready and waits to get the ceiling mounted.
7. The wooden frame is ready and waits to get the ceiling mounted.
8.  ;-) PALEOMAGNETISM = XXX   X   XXXXXX   XXXX   -> Mounting outer shield ceiling plates neither! ;-)
8. ;-) PALEOMAGNETISM = XXX X XXXXXX XXXX -> Mounting outer shield ceiling plates neither! ;-)
9a. Positioning plates of the ceiling’s outer shield.
9a. Positioning plates of the ceiling’s outer shield.
9b. Positioning plates of the ceiling’s outer shield.
9b. Positioning plates of the ceiling’s outer shield.
10. Done so far (August 2025): outer shield of the floor and ceiling are mounted, and corresponding ARM coils are installed.

10. Done so far (August 2025): outer shield of the floor and ceiling are mounted, and corresponding ARM coils are installed.

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