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Re: Tagger design
Tim, Franz,
Another possibility would be to put the microscope BEHIND the fixed
array. The fixed array counters are only 4mm thick, and the entrance
window to the microscope could be located a few cm behind those
counters. The geometry of the microscope works equally well in the two
positions. On the other hand, pushing back the fixed array makes its
support rail substantially longer (several meters) at the downstream end
(9GeV electrons, 3GeV photons). It also makes sense at the low-energy
end of the focal plane (photon energies near the end-point) to have the
fixed array counters right next to the exit window. There the focal
plane deviates substantially from a straight line and having 70 cm of
extra flight path between the focal plane and the tagging counters down
there is not ideal. If we put them next to the exit window there then
we might as well design it that way along the entire focal plane.
In the present design, we are configuring the fixed array to be able to
do endpoint tagging without the microscope, just using the fixed array.
With the latest microscope design, there is now the added possibility of
reconfiguring the microscope for endpoint running and moving it down
there behind the fixed array in case one wants the highest tagging
resolution and rates at the highest energies. Given the low profile of
the fixed array and the extended support that is needed to hold it, I
think it makes the most sense to put it next to the exit window and
mount the microscope behind it on a movable table.
Richard Jones
Tim Whitlatch wrote:
> Hi Richard,
>
> We can move it back as far as you wish (within reason). When all the
> numbers and locations are agreed upon, we will update the drawings to
> reflect the changes.
>
> Cheers,
>
> Tim
>