Re: BCAL dimensions (fwd from George)

[Elton Smith <elton@jlab.org>]

---------- Forwarded message ----------
Date: Thu, 17 Jul 2008 17:37:03 -0600
From: George Lolos <gjlolos@uregina.ca>
To: Beni Zihlmann <zihlmann@jlab.org>
Cc: halld-cal@jlab.org, George Lolos <George.Lolos@uregina.ca>
Subject: Re: BCAL dimensions

Hi Beni:

Tim has all the exact dimensions and has even drawn a
"blueprint-quality" diagram of the module for machining.

George
On 17-Jul-08, at 8:02 AM, Beni Zihlmann wrote:

> Hi George,
> Thank you for this info, I was under the assumption that the aluminum
> would also be grooved.
> Can you tell me then what the exact dimensions will be for the
> lead/scintillator matrix of one module?
>
> cheers,
> Beni
>> 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
>>
>>
>
>