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Re: FDC cableing



Hall D Electronics:

 To Elton:  I am more worried about the high frequency than the low. Any 
low frequencies can be filtered out without affecting data, so removing 
the braid still sounds good to me.

 To Fernando: The large amount of copper in the braid is much denser 
than any of the plastic and is a radiator. If we can get half to 3/4 of 
it out of the cable, that has to be a huge improvement on the multiple 
scattering front. With hundreds of cables there is over a thousand ft of 
cable in the bore, it would probably remove > 25lbs of copper from the 
active area. It will also decrease the diameter over all.
Joe




Fernando J. Barbosa wrote:
> Hi Joe, Gerard, Dave and Elton,
>
> One more suggestion?
>
> I suggest we get a full picture from the manufacturer regarding their 
> design criteria for the electrical and non-electrical specs before we 
> start designing a new version of the cable. I am not convinced that 
> removing the braid will improve things. After all, we have space and 
> the metal in the braid is a small fraction of the total material, right?.
>
> I also concur that whatever we order must be in the final design 
> configuration.
>
> Regards,
> Fernando
>
> Joe Beaufait wrote:
>> I am glad we have decided to go ahead and purchase a sample of the 25 
>> pr. cable. This cable is going to be the standard for much of the 
>> data acquisition system and it would be very nice to see how hard it 
>> is to work with.
>>
>> On that note, there were some comments made at the Wednesday FDC 
>> meeting  concerning the possible redesign of the cable. Daniel 
>> mentioned that we might ask to make the outer jacket thiner and I 
>> promised to look into it but, while looking at the cable diagram I 
>> also noticed that this cable is double shielded. It has an aluminized 
>> mylar layer with drain wire, and a copper braid. I believe we could 
>> do away with the copper braid and reduce the copper in the cable by 
>> at least half.
>>
>> I would like comments from the group on whether or not you would like 
>> me  to pursue this.
>>
>> Thanks
>> Joe
>>