Re: FCal

[Tim Whitlatch <whitey@jlab.org>]

Hi Elke,

I have spoken with Dave Kashy and had some input from Matt Sheppard. 
Each block supported it's own pmt by a brazed bronze sleeve. The stack 
of blocks were supported by very stiff frame. The frame was liquid  
cooled to lower the temperature of the blocks and stabilization of 
temperature (lead tungsten requires this for good transmission). This 
design does allow you to have the blocks in almost any configuration, 
but is is complex and expensive.

Cheers,

       Tim

Elke-Caroline Aschenauer wrote:
> Dear Tim et al.,
>
> something to think about. On Saturday Curtis and I talked to the primex
> people and Ashot mentioned that the primes calorimeter is staggered with
> out supporting the lead-tungsten and lead glass blocks.
>
> The have quite some blocks and what i understood the calo weighs 8 tonnes.
> Mt question is why do we need a support structure for the FCal. Dave Kashy
> was involved in the design of the primex calorimeter, maybe we can talk to
> him ones on this issue.
>
> One reason why I'm asking is that there is the idea to reuse the Primex
> blocks for the inner part of the FCal. one thing is they are only 20x20
> mm^2 but the other issue is there might be an upgrade for the FCal to
> replace some of lead glass blocks with time with lead tungsten ones. so we
> would need a new cellular wall and so on and so on. Of course the
> staggering does not work for a round calorimeter, but do we need really a
> round one. Okay we have to think this over a bit.
>
> Cheers elke
>
>
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