Mounting of the Detector and cable connections via vacuum feedthrough
RoentDek provides the FT12 and FT16 products (with or without mounting option) to allow a proper cable feeding through
the vacuum wall. The FT16 is a combination of an FT12 feedthrough and an FT4 feedthrough (the latter also used for the
DET40/75 timing detectors). These products can be completed by airside decoupling circuits forming the FT12TP and
FT16TP products (not for operation with older DLATR6/8 units). The maximum voltage rating of the FT12 and the standard
FT4 feedthroughs is 4kV, likewise, the flange mounting is also specified up to this rating
*
. The detector can either be custom-
mounted to an experimental setup or to a mounting flange.
RoentDek provides a product option for each detector type for
mounting it onto a flange of “Conflat” norm. The minimum (and default) size of the flange is given by the detector dimension.
However, mounting on larger flanges are possible and often beneficial.
If you do not want to or cannot mount the detector in such a way it is strongly recommended to still use the
RoentDek
FT12TP or FT16TP cable feedthrough(s) and signal decoupling plugs. For a custom mount to an existing experimental setup
we recommend using the outermost threaded holes (in the “holder”) to fix the detector to your experimental setup, e.g.
employing the supplied threaded rods in the shipping mount. Please note that the holder plate/the threaded rods will usually
be biased during operation at a different potential than the mating part of your experimental setup. A proper insulation is
needed. One (or two for FT16TP) DN35CF port(s) must be in the vicinity of the detectors (distance <50cm).
Notice: It is important to have at least 2mm distance between any part of the detector and any other metal part of a
setup, unless the voltage difference is small during operation.
As a thumb-rule, at least 1mm distance for every 1000V of voltage difference should be allowed, assuming also absence of
sharp edges or tips.
If this is not fulfilled, discharge can occur during operation with the consequence of possible damage of the detector
or the electronics.
One can use sheets of Kapton for security if distances appear too small for safe operation. Please contact RoentDek for
options.
The vacuum port where the detector is mounted must have at least 100mm open diameter for
DLD40
DLD80,
HEX80/HEX75
DLD120
HEX120 and DLD150
. If the detector shall come
to rest within the port/tubing of this minimum diameter it may be required to care for extra insulation.
2.1 Mounting of the Detector on a Vacuum-Flange
If you have purchased the flange mounting option fix the stainless steel support ring via the outer threaded M2 rods to the
delay-line anode. You may use one of these thread bolts to supply the anode holder voltage with an appropriate cable. Allow
at least 30mm distance between support ring and delay-line anode.
Then mount the support ring with 8 ceramic insulators and 8 nuts using the M3 threaded bolts onto the flange. The threaded
bolts are grinded at one end. This end must be on the flange side to avoid air pockets in the tapped holes of the flange. The
HEX80 and DLD150, HEX120 or any other detector’s mounting on a CF250 or CF300 flange, special M6-to-M3 adapter
rods are provided.
Please note that the ceramic insulators will not tolerate excessive force when fixing the nuts.
Adjust everything parallel to the flange and fix the nuts. The height above flange of the detector can be varied by choosing
specific distances for fixing the nuts on the M2 and M3 rods. Make sure to allow sufficient distance for slipping the wire contact
pins for the delay-line-terminals on and off. In case you need to further reduce distance to the flange it is possible to alternatively
contact the cable pairs by 2mm lugs and nuts on the wire terminal. Please see advice from
RoentDek before choosing this
option.
Additional cartoons and drawings about the mounting of the DLD and HEX detector to a mounting flange can be found on
our Web Site.
*
Please contact RoentDek for options of biasing MCP front up to -6kV or for special mountings/signal decoupling rated
to even higher voltage (“floated detector operation”).
MCP Delay Line Detector Manual (11.0.1304.1) Page 23 of 83
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