Re: electronic channels (fwd)

[Elton Smith <elton@jlab.org>]

---------- Forwarded message ----------
Date: Mon, 05 Apr 2004 16:39:02 -0400
From: Ravi Kiran Anumagalla <ravi@jlab.org>
To: Paul Smith <ptsmith@indiana.edu>
Cc: Elton Smith <elton@jlab.org>, brindza@jlab.org
Subject: Re: electronic channels

Hi All,

I would like to update on the space calculations of the cables I have been
working on,Pls refer the attached pictures for a detailed explanation. As
indicated earlier, the number of cables required are listed below.

         Detector
Channels/Cables                      Cable Type

Forward Drift Anodes
2880/180                         Coax Ribbon(3mm thk)
Forward Drift Cathodes
5760/360                         Twisted Ribbon (2mm thk)
Central Drift Anodes
3360/210                         Coax Ribbon(3mm thk)

1> The CDC cable connectors are located on the surface of the CDC disc at the
downstream end,210 connectors are modeled to suit the exact number of cables
listed in the table above.  pls refer slide 28 in the power point
presentation file below:

http://www.jlab.org/~ravi/hall/hallD/gluex.ppt

2> The closest cables shown on "slide 30" nearest to the CDC are the 1/4 " HV
cables. I have assumed each package(i.e FDC and CDC) to use 24 cables, As
shown in the picture, we have 72, 1/4 " cables, the remaining 24 tubes are
shown to indicate gas connections for the FDC's.Hope this number is
reasonable???

3> On the 5cm of gap between the CDC/FDC and the Barrel Calorimeter, 10
layers have been modeled to accommodate the 540 cables, each layer has 61
cables located on the circumference of the CDC, 10 layers account to a total
of 610 cables. An extra 70 cables have been included to indicate that we have
additional space. The cables have been modeled by including a space of 1mm
between them, this allows comfortable assembling of the cables.

An insight of the AREA available.

Area b/w the CDC/FDC and Barrel Calorimeter =                   1965  sq cm
Area of 610 cables,considered 3mm thk for the worst case =      856.5 sq cm
Area of 72, 1/4" cables
=       23 sq cm
Area of 3 thk
rails                                                            =       156
sq cm

The space occupied by the cables along with the thk rails accounts to 52.7 %
of the total area available.
Let me know if you all have any comments.

Thanks
Ravi




Elton Smith wrote:

> HI Ravi,
>
> It is misleading to talk about a 10 cm gap. There is only a 5 cm gap which
> goes all the way around the circumference. Assuming there are cables all
> around, I'm afraid you are double-counting when you talk about 10 cm.
>
> See other notes below:
>
> Elton Smith
> Jefferson Lab
> elton@jlab.org
> (757) 269-7625
>
> On Thu, 25 Mar 2004, Ravi Kiran Anumagalla wrote:
>
> >
> > Paul,
> >
> > Thanks for the data on the cables,.
> >
> > I would like to summarize on the space occupied by cables for the
> > various detectors indicated in the
> > Design Rep V4,pg 203.For now , I was looking into the space occupied by
> > the cables between the gap of
> > CDC/FDC and Barrel calorimeter. we presently have a gap of 10 cm
> > The # of channels are indicated in the table below are for Forward Drift
> > Chambers and Cylindrical Drift Chambers.
> >
> > Detector                                     Channels
> >
> > Forward Drift Anodes                    2880
> > Forward Drift Cathodes                 5760
> >
> > The above listed detectors use ribbon cables,For 8640
> > channels(2880+5760) we need 540 ribbon cables, the length of a ribbon
> > cable is ~5cm, we have a diameter of 120 cm (377cm is the
> > circumference)for the CDC,one layer of ribbon cables would be occupied
> > by 75 cables, 540 cables can be accommodated in 7 layers. 7 layers
> > occupy a space of 1cm, this leaves with a space of 9cm for the other
> > cables, i would try to include the cables in the CAD model, hope this
> > wud help.
>
> For the anodes (2880) we might use ribbon coax. As far as size is
> concerned, however, they can be treated the same as ribbon cable.
>
> >
> > Questions:
> > 1> Coming over to the Central drift anodes(3360 channels) which use RG58
> > coax, are the connectors being located on the CDC??
>
> The CDC anodes will likely use ribbon cables for signal. In addition there
> will be a limited number of cables for high voltage (e.g. 3360/100 = 35).
> The high voltage cables could be as large as RG-59, but might be smaller.
>
> > 2> Do we have any gas channels going in the 10 cm gap, if yes, do we
> > have a number where i can include them in my model
>
> For the gas system, you might want to look at the presentations by the CMU
> group at the December collaboration meeting, and/or talk to them.
>
> > 3> Do you think it would be necessary for us to have cables included in
> > the CAD models for all the detectors??
> >
>
> I think a space for cables is needed in the CAD models which would
> indicate the space that is required. However, a layout of individual
> cables is probably not necessary, at least at this time when were are
> still deciding which side of the solenoid the drift chambers are to be
> inserted/removed.
>
> Cheers, Elton.
>
> > Thanks
> > Ravi
> >
> >
> >