Ametek ORTEC MOBIUS-B, User Manual, Page: 15 / 28

805709F / 1115 ORTEC
® MÖBIUS™ HPGe Detector Cooling System
9
3. INSTALLATION
Installation requires at least two people (better
still, three) and a step-stool. Specific shield config-
urations call for specific installation methods.
However, installing the MÖBIUS is essentially no
different than installing a standard 30 L dewar
because the two are very similar in size. The
detector/cryostat assembly should be dry and
warm and the MÖBIUS empty.
The mounting surface must be flat and horizontal.
The shield and/or MÖBIUS must not be positioned
so that it is difficult to disconnect the MÖBIUS
from the electrical supply. Orient the dewar so its
ventilation openings and filter are not blocked.
Figure 10 is an exploded diagram of a typical
spectroscopy system with a PopTop detector, PV4
vertical dipstick cryostat, Model HPLBS shield with
split center plug, and MÖBIUS.
Figure 11 shows a typical MÖBIUS installation
under an HPLBS shield. Setting the detector height
involves the interplay of shield height (adjustment
typically requires a hydraulic jack and wrench), the
thickness of acoustic damping material and/or
other spacers under the dewar, and the insertion
depth of the cryostat cooling rod in the dewar.
Note the arrangement of damping and spacer
materials under the dewar necessary to bring it to
the correct height. Various thicknesses of foam
are used on the bottom (i.e., contacting the floor).
The foam is followed by the plywood spacer, and
the anti-vibration pad is on top.
Order is important
for the various spacers: Foam on the bottom,
followed by the plywood, followed by the anti-
vibration mat.
For installations where there is not enough room
for all three layers,
omit the foam first, then the
plywood, then the anti-vibration mat as a last
resort
.
The detector can also be raised by adjusting the
collar position on the cryostat. This is useful when
using a center plug to reduce floor shine. Note
however that this adjustment lifts the cryostat
cooling rod out of the LN2 column, reducing the
effective capacity of the dewar. In such cases, the
detector begins to warm as soon as the LN2 level
Figure 10.