Elekta Neuromag, Техническое руководство

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8 NM20216A-F
1
Technical data
Noise performances for all operational channels are the following:
• Gradiometer noise (white noise, 60Hz < f < 70Hz): max. 5 fT/(cm
Hz
) for 96% of channels, max. 10 fT/(cm
Hz
) for all gradiometer
channels
• Magnetometer noise (white noise, 60Hz < f < 70Hz): max. 5 fT/
Hz
for 96% of channels, max. 10 fT/
Hz
for all magnetometer channels
• Gradiometer noise (low frequency, 1Hz < f < 2Hz); max. 12 fT/(cm
Hz
) for 96% of channels, max. 20 fT/(cm
Hz
) for all gradiometer
channels
• Magnetometer noise (low frequency, 1Hz < f < 2Hz); max. 12 fT/
Hz
for 96% of channels, max. 20 fT/
Hz
for all channels
1.1.3. Probe unit construction
• Wiring unit: printed circuit board plates, a flexible support tube and a
support shell onto which the triple sensor elements are mounted with
connectors. Twisted pairs between the dc-SQUIDs and the printed
circuit boards on the top of the wiring unit where the components for
the dc-SQUID gain control reside.
• Connection wiring: flexible cable assembly from the printed circuit
boards to the top flange
• Top flange: preamplifiers and connectors for the cables to the elec-
tronics unit
• liquid He-level probe: integrated, superconducting
• Helium siphon: fixed, connects to a flexible part used in transfers
• Thermometers: two Pt-thermometers for monitoring the cool-down
and warm-up of the system
1.1.4. Dewar
• Lower end: helmet-shaped
• Shape of the helmet is based on the EN960:1994 standard
• Circumference of helmet outside surface: 629 mm
• Maximum length of the helmet opening: 222 mm
• Maximum width of the helmet opening: 181 mm
• Maximum inside height of the helmet: 210 mm
• Distance from the surface at liquid helium to the outer room temper-
ature surface against the subject’s head: typically 18 mm
• Thermal radiation shielding: superinsulation and a thermally an-
chored shield
• Material of construction: fiberglass composite
• Total volume of Helium 78 liters