Freiberg
Instruments
GmbH
ּ Am St. Niclas Schacht 13 ּ 09599 Freiberg – Germany
58 / 78
Position sensors
Retracting spring
radiation source source holder
shutter
Fig. 6
Radiation source module (bottom view, transport safety plate removed)
Left: shutter closed; Right: shutter open
The radiation source is safely contained in the radiation source module. The radiation source
is mechanically fixed in a holder ensuring accurate positioning over the sample during
irradiation. The only movable part of the radiation source module is the shutter, so there is no
mechanical load on the source.
With the shutter being in its “closed” position, the downwards-facing radiation exit window is
completely covered by a 1 mm stainless steel shutter (fig. 6). For sample irradiation (typically
between one and ten minutes of duration) the shutter will be opened by a pneumatic cylinder.
The actual shutter position will be detected by two non-contact sensors. In the case of failure
of electrical power or pressurized air supply the shutter will automatically close due to a
retracting spring. Due to its bifurcated design the shutter doesn’t only cover the radiation exit
window of the source but also protects the quartz glass windows from scattered beta
radiation.
The radiation source module is firmly attached to the base plate of the
lexsyg
by special
screws. A 5 mm lead lined housing surrounding the source module (not shown in fig. 2, see
also fig. 12) reduces dose rate and occupational exposure. The housing of the
lexsyg
is fully
closed and locked during rou
tine operation, assuring that the radiation source isn’t accessible
to the standard operator or any other person.
