[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: BCAL dimensions



Hi Beni:

It's my understanding that the 8 mm Al plate glued in the inner face of
the BCAL will be glued on top of the last Pb layer not the fibers.  I
worry that the non-grooved Al plate will not adhere to the fibers and
any delamination there will pull fibers out!  If we glue the plate on
the last Pb layer, we can use industrial epoxy, the same we use for the
base Pb layer, and assure that the Al-Pb bond is the strongest possible.
 This will make it also more robust for the machining stages.

George

>>> Beni Zihlmann <zihlmann@jlab.org> 07/16/08 2:27 PM >>>
Hi calorimeter experts,
I want to make sure that we have in the monte carlo a description of the

BCAL
that comes as close as possible to what will be built in reality.
Currently the following is in the MC.
from radios 65 cm to 87.46 cm we have the lead/scintillator/glue 
mixture  and then a  2.54 cm
Aluminum plate.
Now in the actual construction the last lead layer to be glued on will 
be replaced by 8mm of Aluminum
which corresponds to about the same radiation length as the 0.5mm lead. 
In Order to reflect this in the
MC I propose the following:
make the active volume of the lead/scintillator/glue material 1.328mm 
shorter and add 8mm of aluminum.
the 1.328mm lead/scintillator/glue is 8.9958% of one radiation length 
the same amount at the 8mm aluminum.
In this way we will have only a difference of 0.8mm in thickness for the

whole BCAL wedge between what
is in the MC and what will be built but we will have the same radiation 
length.

any opinions?
Beni